Hermit crabuloid

The Hermit Crabuloid appears to be a normal hermit crab at first glance. However, its shell is completely impervious to weapon fire and the Crabuloid is equipped with a short-range weapon it uses when it's right next to a target.

Normally, the Crabuloid appears to be a seashell in the middle of nowhere. However, when a target gets close, it will start chasing them in order to hit it with its melee attack.