Board Thread:Fun and Games/@comment-38808443-20190412044956/@comment-33621007-20190414144936

It looks like you have found a fossil. They are very rare and can be found in deserts and swamps underground. Some bone blocks have a chance to be replaced by coal ore.

More info can be found below

The Offical Minecraft Wiki

Yes and I do work at the FANDOM Minecraft Wiki.