Block of Bones

Block of Bones (Bone Block) is a block you can craft with 9 bones, and obeys gravity. If dropped from higher than 3 blocks, it will break into 9 bones, same if you mine it. There are also Slabs, that can be made with 3 bones, does not obey gravity but can break into 3 bones if mined.

Found in...

Dungeons

Sometimes replaces Chests or Monster Spawner.

Strongholds

Near the lava for the End Portal.

Mineshaft / Jungle Temple

Ontop of Cobwebs.

Desert

Randomly slabs place instead of Dead Bushes.

Desert Temple

On the corners in the trap chest room.

The Nether

in Nether Forrtress