Thw new ore introduced by BoneCraft is called Fossil Ore. It looks like this :
Fossil ore can be found below sea level at a similar fequency and ore cluster size (between 6 - 10) as Iron ore. When mined with any pickaxe, it will drop between 1 - 3 bones.
As you can now collect more bones, Bonecraft allows you to make a tools and a full suit of armor using bones. They have a similar protection and durability to iron. Check out the item pages for recipes.