Bone Serpent

The Bone Serpent is the strongest non-boss burrowing enemy.Every part except the tail has 150hp,the tail has 200hp.They can move trough any block and are not effected by lava or drowning.Destroying one part of a Bone Serpent will kill it.It may very rarely drop Sunfury,one of the strongest weapons in the game.The only more powerful burrowing enemy is the Eater of Worlds.