Fossilised Mobs

Fossilized Mobs is a NeoForge mod for Minecraft 1.21.1 that adds a new fossil-hunting progression to every dimension. While mining, players can discover fossilized versions of stone, deepslate, netherrack, and end stone. These blocks generate naturally in newly created chunks, replacing small amounts of their normal surrounding material. Fossilized stone is found in the Overworld’s ordinary stone layers, fossilized deepslate is found deeper underground, fossilized netherrack appears throughout the Nether, and fossilized end stone appears in the End.

Each fossil block contains the remains of creatures associated with its dimension. Breaking a fossil block with a pickaxe drops one random fossilized spawn egg from that block’s mob pool instead of dropping the block itself. Fossilized eggs cannot spawn creatures directly; they must first be revived. Place any fossilized spawn egg and one water bucket anywhere in a crafting grid to receive the normal Minecraft spawn egg for that creature. The water bucket is returned as an empty bucket, allowing it to be used again.

Fossils are intentionally much easier to discover in version 1.1.0. Fossilized stone and netherrack make four vein attempts per chunk, while fossilized deepslate and end stone make three attempts per chunk. They only generate in terrain that has not already been explored, so players should create a new world or travel into new chunks after installing the mod.
Every fossilized egg has a unique darkened texture based on the colors of its normal Minecraft spawn egg. This makes the eggs recognizable while giving them an aged, mineral-darkened appearance.

This recipe creates one spawner block. All fossil blocks and fossilized eggs are also available in the Fossilized Mobs creative-mode tab for easy testing and building.