{
  "feature": "upgrade_aquatic:prismarine_coral",
  "placement": [
    {
      "type": "minecraft:carving_mask",
      "step": "air"
    },
    {
      "type": "minecraft:rarity_filter",
      "chance": 450
    },
    {
      "type": "minecraft:biome"
    }
  ]
}