{ 
  "type": "minecraft:jigsaw", 
  "biomes": 
  [ "minecraft:badlands", 
  "minecraft:desert", 
  "minecraft:forest", 
  "minecraft:jungle", 
  "minecraft:lush_caves", 
  "minecraft:old_growth_pine_taiga", 
  "minecraft:plains", 
  "minecraft:savanna", 
  "minecraft:mangrove_swamp", 
  "minecraft:deep_dark" ], 
  "step": "underground_structures", 
  "spawn_overrides": {}, 
  "start_pool": "minecraft_121_update:trial_chamber",
  "size": 7,
  "start_height": { "absolute": 0 },
  "max_distance_from_center": 80,
  "use_expansion_hack": false }