Decorator Crab

Decorator Crabs do exactly what the name promises: they actively attach living sponges, algae, and other small organisms to hooked bristles on their own shell, building a genuine, growing camouflage suit out of whatever material is available in their environment. It's not passive debris collection, it's deliberate — the crab will select and place material by hand, and a decorator crab moved to a new tank will often re-decorate itself using whatever's locally available within days. Peaceful, slow-moving, and one of the more genuinely fascinating behavioral quirks you can watch play out in a reef tank's cleanup crew.