Crustoccupas are soft-bodied, and have two grasping appendages that branch from the base of the mouth. Their tail is large, hard, and hinged. The two parts are concave.
These creatures eat various types of debris and flotsam floating around in the seas.
When threatened, crustoccupas hinge their tail backwards so that, due to the tail parts' concave shape, the animal is enclosed in a hard shell that is difficult to break open.