A burster in Hellfire Peninsula.
Bursters are worm-like creatures that can be found in Outland. They hide from danger in loose soil, and also emerge when prey is near to pounce upon it. They cannot be attacked while they are underground by weapons or spells. Even when you do engage them in combat above ground, they will try to burrow back under and jump out again behind you. You can tell when one is near by the movement of soil.