seedlookoutOVERWORLD · SMALLER FEATURES
Monster Room
Page updated
Monster rooms, usually called dungeons, are small cobblestone rooms with a monster spawner and usually loot chests. Players raid them for early supplies and build experience and mob-drop farms around the spawner.
This guide follows vanilla Java 26.3. Historical changes retain their own edition and version. Bedrock generation and loot can differ. Screenshots and verified seeds below retain their own game versions.
28462718234064871 · Java 26.3 · overworldReference capture · Naturally generated structure, photographed in Minecraft Java 26.3.Game data and source research
Where it generates in Java 26.3
The Overworld biome definitions include both ordinary and deep monster-room placement passes, including Deep Dark. This feature inclusion is separate from ordinary natural-mob spawning rules. [1][3][4]
Placement and frequency
The ordinary placement pass makes ten attempts with sampled origins from Y=0 toward the world top. The deep pass makes four attempts from six blocks above the world bottom through Y=-1. Fourteen attempts do not mean fourteen rooms: biome and cavity checks can reject them. [1][2][4]
Conditions and limits
Before building, the feature requires solid blocks across its tested floor and roof. It counts positions around the side boundary with two vertically adjacent air blocks and accepts only one through five such openings. The horizontal interior radii are sampled independently, so room width and length can differ. [1][2][4]
A cobblestone room built around a spawner
A monster room is a small, roughly rectangular cobblestone enclosure with a mossy floor and a central spawner. The generator chooses each horizontal interior span as five or seven blocks before considering existing openings and protected blocks. It is a procedural feature, not a saved room template. [5]
The feature attempts two chest placements, trying several candidate positions against walls. Those attempts can fail, so the familiar two-chest layout is not guaranteed. Check the actual walls before concluding a chest is buried outside the room. [5]
A repeatable source of one mob type
The spawner mob selector contains skeleton, zombie, zombie and spider entries, producing a 25% skeleton, 50% zombie and 25% spider choice at this selection step. These are spawner-type selection probabilities, not mob counts or the chance of finding a monster room. [5]
The spawner remains a continuing encounter source while its conditions are met. Killing the current group does not clear the source. The feature does not choose cave spiders, creepers or silverfish in this mob list. [5]
Loot and rewards in Java 26.3
The monster-room chest uses simple_dungeon loot, independently of the room spawner. Java 26.3 makes 1-3 valuables selections from weight 144, 1-4 supply selections from weight 125, and three material selections from weight 40. [6]
The valuables pool includes Otherside, 13 and Cat discs, enchanted golden apples, name tags and randomly enchanted books. Otherside and the enchanted apple each weigh 2, while 13 and Cat each weigh 15. The table does not include an armor-trim draw. [6]
A monster spawned by the room follows its own entity drop rules. The probabilities here describe an actual assigned chest and do not promise a fixed number of surviving chests or any special spawner drop. [6]
Compared directly with Java 1.20.1, the Java 26.3 tables differ. The inspected simple dungeon table gains Copper horse armor, Leather and no longer lists Saddle; its first pool changes from total weight 129 to 144. Use the current weights rather than carrying older chest percentages forward. [6][8]
| Item | Where the rule applies | What the data establishes |
|---|---|---|
 Enchanted golden apple | One monster-room-table chest | 2.8% chance of at least one apple selection. [6][7] |
 Music disc Otherside | One monster-room-table chest | 2.8% chance of at least one disc selection. [6][7] |
 Music disc cat | One monster-room-table chest | 19.4% chance of at least one disc selection; 13 has the same weight. [6][7] |
 Name tag | One monster-room-table chest | 25.3% chance of at least one name-tag selection. [6][7] |
Version history and release dates
These milestones retain their edition and exact build labels. Snapshot, beta and preview dates belong to those development builds; full releases and staggered Pocket platform releases are dated separately. Historical introduction claims come from the cited Wiki history. [9]
| Version | Released | What changed |
|---|---|---|
| Java Infdev 20100625-1917 | June 25, 2010 | Introduced dungeons with monster spawners and loot chests. [9][11] |
| Java Alpha 1.0.14 | July 30, 2010 | Added the 13 and cat music discs to dungeon loot. [9][12] |
| Java 1.4.6 | December 20, 2012 | Added enchanted books to dungeon chests. [9][13] |
| Java 1.6.1 | July 1, 2013 | Added name tags to dungeon loot. [9][14] |
| Pocket 0.9.0 | July 10, 2014 | Introduced dungeons in Pocket Edition. [9][15] |
| Java 1.18 | November 30, 2021 | Monster rooms became more frequent, especially below Y=0. [9][16] |
| Java 1.21.6 | June 17, 2025 | Replaced saddle loot with 1–5 leather. [9][17] |
| Java 1.21.9 | September 30, 2025 | Added copper horse armor to monster-room chest loot. [9][18] |
SeedLookout in-game verification
Screenshots
28462718234064871 · Java 26.3 · overworldReference capture · Naturally generated structure, photographed in Minecraft Java 26.3.Our screenshots of naturally generated structures in Minecraft. Each caption gives the seed, coordinates and version. Select one to open it at full size.
Seeds with this monster room
None of our verified seeds includes this structure yet. The guide cites game data, code analysis and other references; it does not verify a seed.
Sources
References identify the edition, version and evidence behind the guide. Game code and data describe generation rules; the seed table records locations checked in game. Research reviewed 2026-10-02.
- Mojang Java 26.3: feature configuration ↗
Inner archive META-INF/versions/26.3/server-26.3.jar: data/minecraft/dimension_type/overworld.json; data/minecraft/worldgen/feature/monster_room.json; data/minecraft/worldgen/noise_settings/overworld.json
Evidence details
Official server SHA-1 33680f5f2ac32864d6d7cf5e56a705fdb3e05f4c. SHA-256 by archive member: data/minecraft/dimension_type/overworld.json = d1fc489f93934f77d855e721bd822595aa1e44460342f0e5ce9de7e2dfc9e10e; data/minecraft/worldgen/feature/monster_room.json = cc34d3c77807d3bad92a247eaefbdcf8a6ae8bb604a4247b214775b37f1ba42c; data/minecraft/worldgen/noise_settings/overworld.json = d093895d50edd79d53555b33b62d767115399764e32a4f9ae2687739f785d4b9
- Mojang Java 26.3: feature placement inputs ↗
Inner archive META-INF/versions/26.3/server-26.3.jar: data/minecraft/worldgen/placed_feature/monster_room.json; data/minecraft/worldgen/placed_feature/monster_room_deep.json
Evidence details
Official server SHA-1 33680f5f2ac32864d6d7cf5e56a705fdb3e05f4c. SHA-256 by archive member: data/minecraft/worldgen/placed_feature/monster_room.json = d14b9c71284c282df35ebab73f89a10822bf9ebbb4405db6d61f19fce454a46e; data/minecraft/worldgen/placed_feature/monster_room_deep.json = 6a4f126f1af2800170ac37d379db0647c0d3598e0910df7c9c6592daec22d10b
- Mojang Java 26.3: biome feature lists ↗
Inner archive META-INF/versions/26.3/server-26.3.jar: data/minecraft/worldgen/biome/badlands.json; data/minecraft/worldgen/biome/bamboo_jungle.json; data/minecraft/worldgen/biome/beach.json; data/minecraft/worldgen/biome/birch_forest.json; data/minecraft/worldgen/biome/cherry_grove.json; data/minecraft/worldgen/biome/cold_ocean.json; data/minecraft/worldgen/biome/dappled_forest.json; data/minecraft/worldgen/biome/dark_forest.json; data/minecraft/worldgen/biome/deep_cold_ocean.json; data/minecraft/worldgen/biome/deep_dark.json; data/minecraft/worldgen/biome/deep_frozen_ocean.json; data/minecraft/worldgen/biome/deep_lukewarm_ocean.json; data/minecraft/worldgen/biome/deep_ocean.json; data/minecraft/worldgen/biome/desert.json; data/minecraft/worldgen/biome/dripstone_caves.json; data/minecraft/worldgen/biome/eroded_badlands.json; data/minecraft/worldgen/biome/flower_forest.json; data/minecraft/worldgen/biome/forest.json; data/minecraft/worldgen/biome/frozen_ocean.json; data/minecraft/worldgen/biome/frozen_peaks.json; data/minecraft/worldgen/biome/frozen_river.json; data/minecraft/worldgen/biome/grove.json; data/minecraft/worldgen/biome/ice_spikes.json; data/minecraft/worldgen/biome/jagged_peaks.json; data/minecraft/worldgen/biome/jungle.json; data/minecraft/worldgen/biome/lukewarm_ocean.json; data/minecraft/worldgen/biome/lush_caves.json; data/minecraft/worldgen/biome/mangrove_swamp.json; data/minecraft/worldgen/biome/meadow.json; data/minecraft/worldgen/biome/mushroom_fields.json; data/minecraft/worldgen/biome/ocean.json; data/minecraft/worldgen/biome/old_growth_birch_forest.json; data/minecraft/worldgen/biome/old_growth_pine_taiga.json; data/minecraft/worldgen/biome/old_growth_spruce_taiga.json; data/minecraft/worldgen/biome/pale_garden.json; data/minecraft/worldgen/biome/plains.json; data/minecraft/worldgen/biome/river.json; data/minecraft/worldgen/biome/savanna.json; data/minecraft/worldgen/biome/savanna_plateau.json; data/minecraft/worldgen/biome/snowy_beach.json; data/minecraft/worldgen/biome/snowy_plains.json; data/minecraft/worldgen/biome/snowy_slopes.json; data/minecraft/worldgen/biome/snowy_taiga.json; data/minecraft/worldgen/biome/sparse_jungle.json; data/minecraft/worldgen/biome/stony_peaks.json; data/minecraft/worldgen/biome/stony_shore.json; data/minecraft/worldgen/biome/sulfur_caves.json; data/minecraft/worldgen/biome/sunflower_plains.json; data/minecraft/worldgen/biome/swamp.json; data/minecraft/worldgen/biome/taiga.json; data/minecraft/worldgen/biome/warm_ocean.json; data/minecraft/worldgen/biome/windswept_forest.json; data/minecraft/worldgen/biome/windswept_gravelly_hills.json; data/minecraft/worldgen/biome/windswept_hills.json; data/minecraft/worldgen/biome/windswept_savanna.json; data/minecraft/worldgen/biome/wooded_badlands.json
Evidence details
Official server SHA-1 33680f5f2ac32864d6d7cf5e56a705fdb3e05f4c. SHA-256 by archive member: data/minecraft/worldgen/biome/badlands.json = 11369dfe8a467fdf0a0eca503c538064b5e1827600dce40ee8e295bc4f3c87e6; data/minecraft/worldgen/biome/bamboo_jungle.json = 37c0514ae56eec4b276f5d6610d79b2cad630efebf6b5e90d761512f1881264b; data/minecraft/worldgen/biome/beach.json = afaac383fa28823339b7bb46e0b0b153de0f8560d85dd3bcb671e230b49d4f3b; data/minecraft/worldgen/biome/birch_forest.json = 70b413f475985fe34824e14677f38f4fd4d95ecedb1d36a61748b86a41afc2c1; data/minecraft/worldgen/biome/cherry_grove.json = 6039701fd902424604f4f233d036be8f16f45fc31d20c2835fb16126d44b691e; data/minecraft/worldgen/biome/cold_ocean.json = 2c94f05ed9c19d94cd7db8cb22b2f27c69d7dd8ac6b67e3b784a3b92df84f9ca; data/minecraft/worldgen/biome/dappled_forest.json = 9d163b1468234b0f9d993aa4ac02642fbe0f1dda7d802d95e9bc5e5430d69021; data/minecraft/worldgen/biome/dark_forest.json = db1144042329aa89e153073d6754dc94ce98388d7fbc10e3f3d65fa2aeecfc37; data/minecraft/worldgen/biome/deep_cold_ocean.json = 66638eb5eec06bcee1e072826db88d7d29a6d08cb78b290a3bc2c4cbca66ece0; data/minecraft/worldgen/biome/deep_dark.json = d8d259df069f61cb8db98697680b06d3e6d9b7c6c2825bc6c00fd93b50de6cf1; data/minecraft/worldgen/biome/deep_frozen_ocean.json = 8b84a6fb8f77183ca062db8176c9a6a937997de6c65c12856e49ba72aa503070; data/minecraft/worldgen/biome/deep_lukewarm_ocean.json = 5820b192fa336523aaa50515abe67776190ddb0cfa646b976b0b0fd0eb30150a; data/minecraft/worldgen/biome/deep_ocean.json = 3eaf49b1c6254dee733b8054e65c5b5c4186d17412d1d5907ce0d33a2eb38d45; data/minecraft/worldgen/biome/desert.json = f06ac77d35a883a6ad4470f4588a63a51b304e544f37a47e82cb7b1bdbd0d752; data/minecraft/worldgen/biome/dripstone_caves.json = 21a7e42aac1aacd326a8857869a6af9fbf1686b746ea418616c1e8285f9aea47; data/minecraft/worldgen/biome/eroded_badlands.json = 11369dfe8a467fdf0a0eca503c538064b5e1827600dce40ee8e295bc4f3c87e6; data/minecraft/worldgen/biome/flower_forest.json = cb923ce968b52bd1b606b121785b7a202ace5d6e3ed3ee92f4913da6d689221b; data/minecraft/worldgen/biome/forest.json = 520df8f84b54ec221decbeabbcbd6ebe3fa661e4a193bf8ba0fe38cd1a2867ee; data/minecraft/worldgen/biome/frozen_ocean.json = ce44dce0cc53d47bbade57fd048dd6947858157b2f99b1b48829c67ebc8e1ece; data/minecraft/worldgen/biome/frozen_peaks.json = 880a2b23833dc7a2fba30123c320e09a1695f2918fc883b3afdb15b782a79b3e; data/minecraft/worldgen/biome/frozen_river.json = 4b7b6a3de4d49478498d3a093097ada01686ec542587488f5208cc543e076210; data/minecraft/worldgen/biome/grove.json = d1db4441a37cc29d94420dfcb0c6a6ed4b291fb72ef7e72b139247e3729925db; data/minecraft/worldgen/biome/ice_spikes.json = d233b026de2bd4f58bb2d79cd9e14b97070f3f533ad100097ace42c0183aabf4; data/minecraft/worldgen/biome/jagged_peaks.json = bfd5d5f0d5939d868c990512f08fcd05e4bd1e543a087306016393927d2cbdb5; data/minecraft/worldgen/biome/jungle.json = 8939db69d35e010cc2ea907a33fd9ee60157f64e5ed654eaab3ab1da1117856a; data/minecraft/worldgen/biome/lukewarm_ocean.json = 6706d57592648bcb2268fd5b2e761d2a0a3d6b91867992384e69176afb05101d; data/minecraft/worldgen/biome/lush_caves.json = 0f57c52f9065eb1671ca6055f1aa8e454b7285993a3bfd377b5b32f28b1b3821; data/minecraft/worldgen/biome/mangrove_swamp.json = c78bb5b8bb3bd35e1ff494ae1191933fbe5ce03fa5578a3c53116251fa56add6; data/minecraft/worldgen/biome/meadow.json = 20c9a9529230dad22432daf79697db7a7bd59baff33466b51a65388337932aad; data/minecraft/worldgen/biome/mushroom_fields.json = 9f35318ebbf30e6a53bb4e9b76f42c626fdb8b2c2ec7ccd9ad3172eeeae378d5; data/minecraft/worldgen/biome/ocean.json = 1922c63e6464248d3a731be06c93f4dc56132c8df21ebff11747c7d0b158a436; data/minecraft/worldgen/biome/old_growth_birch_forest.json = dbc9d24737e4c767db14cc429cd58729b178d3d86d0f4ee514b3fdb04eace388; data/minecraft/worldgen/biome/old_growth_pine_taiga.json = 3d5e2efb563134bebda945fa8dcf424456f08c974b87d59c42798151fe79f472; data/minecraft/worldgen/biome/old_growth_spruce_taiga.json = 7edc93048460c61b766614f2996542996525e37ea0a29042fdf44f7f6ab48ab1; data/minecraft/worldgen/biome/pale_garden.json = 4bf9a943aec87c2ddfec69e5e67c369bddb0f78d81ae7b9acb2544e13af36c10; data/minecraft/worldgen/biome/plains.json = 72ee54bca8e7202664ffa804a81106b2bcfa67dba3ce4472df54deb31f3be69b; data/minecraft/worldgen/biome/river.json = e2a3bada031f2240e5e911f21d1d77b4ef7e7e7b91daccd30f371bd78d82faec; data/minecraft/worldgen/biome/savanna.json = 234daea472a3278933d36836833d0aab653255a266a94c064bbe9d35f68bbba3; data/minecraft/worldgen/biome/savanna_plateau.json = 12a923d090c79c08c44914502b1cb69455e1c7c5352f80f0ca5fc54d0b888406; data/minecraft/worldgen/biome/snowy_beach.json = 3bbddee4593a766d3c26a8f14b54fdd398573b691479c28a0d37eec848bffecf; data/minecraft/worldgen/biome/snowy_plains.json = 1400c9f893d110d9cef77f4a992aa5fd106bd6e752abb667a7b57bde559e044f; data/minecraft/worldgen/biome/snowy_slopes.json = 1cb07ef94dc170679661c8195d6a0c15b9d2dc751c45e5bce9a01cf4918eadbf; data/minecraft/worldgen/biome/snowy_taiga.json = ffda8a33edb392d595cb1ce289a1a610530e376dc11f140d7585e0b1d28daa04; data/minecraft/worldgen/biome/sparse_jungle.json = 9390b5e1b7fc1841fcb747e04b24fe7f39d54094976e89ed67b4d376be509361; data/minecraft/worldgen/biome/stony_peaks.json = 09db7a4e6a779360d350af67d3daa7b35f7259803b2117b8eb2f2cb7638f8f5e; data/minecraft/worldgen/biome/stony_shore.json = de12722c44dd0f947d4e5bd2d397ffdc201518d115c1057fd3433584154f98d3; data/minecraft/worldgen/biome/sulfur_caves.json = 99d90558cd4715a645f4d5837f60558dd669fd05f885b7141996eee4765596f8; data/minecraft/worldgen/biome/sunflower_plains.json = a8664a46c13232553a03af588c42d2f5c260d890b8784929f38c793dcb20dd87; data/minecraft/worldgen/biome/swamp.json = 5fa92e5d6758895a806166342dbea7b50a5e4e31818224106b3bea1b840fbda1; data/minecraft/worldgen/biome/taiga.json = 49a14e1f16e17c9f81719db7c5a58c8ad120ce5960e0153a226f7f9b810a4807; data/minecraft/worldgen/biome/warm_ocean.json = 942a4f2d91b6169e59e85a9d46f4778fe4fe3e3a4d915edde54bd31e95be1bad; data/minecraft/worldgen/biome/windswept_forest.json = 1f244f57bb7dda66d2d056bfcb9d730a958408a24f52559cf2937ea01ec18449; data/minecraft/worldgen/biome/windswept_gravelly_hills.json = 1d6c9c4ab6cc20a4fb699ae63ed3303337e8db431027ce6dc9d74d2ca57d62f5; data/minecraft/worldgen/biome/windswept_hills.json = 1d6c9c4ab6cc20a4fb699ae63ed3303337e8db431027ce6dc9d74d2ca57d62f5; data/minecraft/worldgen/biome/windswept_savanna.json = b4b2f105416ceb863948cbb2c76e34febb11a587e324d97626cc2c8d2c171d96; data/minecraft/worldgen/biome/wooded_badlands.json = 0046ffc76344b50db09f8b13a0d6502c3f4ef49e9d49583d98a0bb84ab7faff6
- Mojang Java 26.3: feature execution and rejection checks ↗
Inner archive META-INF/versions/26.3/server-26.3.jar: net/minecraft/world/level/levelgen/VerticalAnchor$AboveBottom.class; net/minecraft/world/level/levelgen/VerticalAnchor$Absolute.class; net/minecraft/world/level/levelgen/VerticalAnchor$BelowTop.class; net/minecraft/world/level/levelgen/VerticalAnchor$RelativeToSeaLevel.class; net/minecraft/world/level/levelgen/VerticalAnchor.class; net/minecraft/world/level/levelgen/feature/MonsterRoomFeature.class; net/minecraft/world/level/levelgen/heightproviders/UniformHeight.class; net/minecraft/world/level/levelgen/placement/BiomeFilter.class; net/minecraft/world/level/levelgen/placement/CountPlacement.class; net/minecraft/world/level/levelgen/placement/FeaturePlacer.class; net/minecraft/world/level/levelgen/placement/RarityFilter.class. Methods: MonsterRoomFeature.place; FeaturePlacer.place; RarityFilter.shouldPlace; BiomeFilter.shouldPlace; UniformHeight.sample; VerticalAnchor.resolveY; CountPlacement.count
Evidence details
Official server SHA-1 33680f5f2ac32864d6d7cf5e56a705fdb3e05f4c. Implementation inspected using CFR 0.152; reconstructed Java is not an original Mojang source publication. SHA-256 by archive member: net/minecraft/world/level/levelgen/VerticalAnchor$AboveBottom.class = 65e8d275fecd2bc76618395521925e51defa7db48cb4fa2c006118ff4a8471b3; net/minecraft/world/level/levelgen/VerticalAnchor$Absolute.class = ae4092473cdf6800c40e38d887fa79d3c555212ab875cae87e66f323891fb733; net/minecraft/world/level/levelgen/VerticalAnchor$BelowTop.class = 028e41d89c42f9d1b15aea47b6125dc6019e996b97d4dd9e31b399e5bba9907d; net/minecraft/world/level/levelgen/VerticalAnchor$RelativeToSeaLevel.class = dac20a9a8a5d24b1b6f0fc273bd619df71982745ea6dab06723f170afa6f63eb; net/minecraft/world/level/levelgen/VerticalAnchor.class = bd6f44d0714b54bfe084c570d169084e7794a66f8f8283f7f3abbc3d1ff44011; net/minecraft/world/level/levelgen/feature/MonsterRoomFeature.class = 006a3287a6b0d65e6e25840f4aea068bd03ce358cfb99e8281f2a55a6529f742; net/minecraft/world/level/levelgen/heightproviders/UniformHeight.class = 8f157810ef32e632ddf06276eb4874714079c9d8aec7bac11515321a4272570b; net/minecraft/world/level/levelgen/placement/BiomeFilter.class = 9af5f023e371c8541e5a6086e5c01693735e39d10ee918adfea4761fc231e38a; net/minecraft/world/level/levelgen/placement/CountPlacement.class = e2fa737411edc1547e7e9f29d108298fb87b6b03709a6b56fcfa9df1cd30d987; net/minecraft/world/level/levelgen/placement/FeaturePlacer.class = 1d3e9c087bf63463503ba2fb55893053a3e0da6cd38fd3d6302afb02d9be437f; net/minecraft/world/level/levelgen/placement/RarityFilter.class = 816b014fad3a867c2fe487ccb417dc2e347dc8bcba773b4413fc843985dbecc6
- Mojang Java 26.3: monster room layout and encounter implementation ↗
net.minecraft.world.level.levelgen.feature.MonsterRoomFeature; net.minecraft.world.level.BaseSpawner; MonsterRoomFeature.place / randomEntityId; MOBS array and chest placement loop; BaseSpawner.serverTick / delay / isNearPlayer.
Evidence details
Official server SHA-1 33680f5f2ac32864d6d7cf5e56a705fdb3e05f4c; inner META-INF/versions/26.3/server-26.3.jar SHA-256 a362163eec5d1612d520772bc16e5b39c09e3b234fdc045f56bf544284ee8ae6. Official bytecode inspected through CFR 0.152; reconstructed implementation, not an original source checkout.
- Mojang Java 26.3: monster room loot data ↗
Inner META-INF/versions/26.3/server-26.3.jar: data/minecraft/loot_table/chests/simple_dungeon.json
Evidence details
Verified official server SHA-1 33680f5f2ac32864d6d7cf5e56a705fdb3e05f4c. File SHA-256s: simple_dungeon.json: 702739b545cf04176f0c2897d2b56bc9ed074fc9bc517db2347e11084faae5e8. Table identity and conditional item rules are distinct from any particular generated container.
- Java 26.3 monster room: calculated selection odds ↗
Relevant /pools indices in the data reference; LootPool.addRandomItem/addRandomItems; UniformContainerBase.uniformFields; UniformGenerator.getIntUnsafe.
Evidence details
For direct unconditional weighted pools, chance of at least one selection is 1 minus the average of (1−weight/totalWeight)^n over inclusive uniform integer rolls. Values are theoretical table-invocation probabilities, not seed frequencies. Exact inputs: [{"itemId":"minecraft:enchanted_golden_apple","table":"data/minecraft/loot_table/chests/simple_dungeon.json","pool":0,"fraction":"30817/1119744","chance":0.027521469192958392,"weight":2,"total":144,"rolls":[1,2,3]},{"itemId":"minecraft:music_disc_otherside","table":"data/minecraft/loot_table/chests/simple_dungeon.json","pool":0,"fraction":"30817/1119744","chance":0.027521469192958392,"weight":2,"total":144,"rolls":[1,2,3]},{"itemId":"minecraft:music_disc_cat","table":"data/minecraft/loot_table/chests/simple_dungeon.json","pool":0,"fraction":"64445/331776","chance":0.19424250096450618,"weight":15,"total":144,"rolls":[1,2,3]},{"itemId":"minecraft:name_tag","table":"data/minecraft/loot_table/chests/simple_dungeon.json","pool":0,"fraction":"35405/139968","chance":0.25295067443987196,"weight":20,"total":144,"rolls":[1,2,3]}]
- Mojang Java 1.20.1: inspected historical monster room loot ↗
data/minecraft/loot_tables/chests/simple_dungeon.json
Evidence details
Limited comparison of the listed data files; no claim that all intermediate releases share either table. SHA-256s: simple_dungeon.json: 32f14004ab4d7dea19641411d980b98ad19e1658c8674c272eb13dfac39d7626
- Minecraft Wiki: Monster Room — pinned history ↗
History section, retaining edition, release grouping, development-version and experimental-toggle qualifiers.
Evidence details
Pinned article revision 3787526 from 2026-09-21T15:07:37Z. Historical claims only; not an audited game build or release-date source.
- Minecraft Wiki: Monster Room description ↗
Opening description and History
Evidence details
Pinned article revision 3787526; retrieved October 1, 2026. Article history supports historical introductions; current generation and loot are audited separately from game data.
- Java Infdev 20100625-1917: release date ↗
Version infobox |date=June 25, 2010; opening paragraph and additions list
Evidence details
This exact Infdev build is absent from the Mojang launcher manifest. The community release article provides the historical date; no official game binary was inspected for this introduction claim.
- Java Alpha 1.0.14: release date ↗
Version infobox release date
Evidence details
Public release calendar date from pinned version article. Legacy metadata date 2010-07-29 disagrees; its timestamp and URL remain preserved separately.
- Java 1.4.6: release date ↗
Version infobox release date
Evidence details
Public release calendar date from pinned version article. Legacy metadata date 2012-12-19 disagrees; its timestamp and URL remain preserved separately.
- Java 1.6.1: release date ↗
Version infobox release date
Evidence details
Public release calendar date from pinned version article. Legacy metadata date 2013-06-28 disagrees; its timestamp and URL remain preserved separately.
- Pocket 0.9.0: release date ↗
Version infobox release date
Evidence details
Historical date from the pinned Minecraft Wiki version article; introduction is separately attributed to each structure article history.
- Java 1.18: release date ↗
/id; /releaseTime
Evidence details
Date belongs to the exact 1.18 build. Snapshot and prerelease dates are separate from the later full release; metadata does not prove the feature introduction.
- Java 1.21.6: release date ↗
/id; /releaseTime
Evidence details
Date belongs to the exact 1.21.6 build. Snapshot and prerelease dates are separate from the later full release; metadata does not prove the feature introduction.
- Java 1.21.9: release date ↗
/id; /releaseTime
Evidence details
Date belongs to the exact 1.21.9 build. Snapshot and prerelease dates are separate from the later full release; metadata does not prove the feature introduction.
Item art uses vanilla Java 26.3 assets from the official client release. Icons retain their game version alongside the guide.
Descriptions adapted from the Minecraft Wiki retain its attribution under CC BY-NC-SA 3.0. Calculations and code analysis are SeedLookout research. Screenshot captions identify each capture. The seed table contains our published verified seeds; checking a location does not establish particular room contents or chest loot.