Wyrm

A new hostile mob: The Wyrm. Spawns at night, in low to the ground places, above fossils. The Wyrm would be able to bury itself in the ground, like the silverfish. Essentially, imagine a dragon with no wings, no legs, much more snake like, but it can bury underground. And it could resurface on its own hypothetically, or perhaps when it surfaces in the ground, the block it uses to bury itself becomes an "openable, block-mob" similar to that of the Shulker, where the wyrm can exit partially and do damage, by attacking the player, or perhaps it could breathe fire?(That one's probably a lot more complicated but would be fun) The Wyrm doesn't have to be that big either. Just essentially a very big Silverfish.