The Trapezia Pocillopora/Acropora Crab, also known as the Acro Crab, is a small commensal crustacean that lives within the branches of Pocillopora and Acropora corals. It plays a vital role in maintaining the health and survival of its host coral by aiding in water flow, cleaning and defending the coral from predators and invaders. This symbiotic relationship benefits not only the crab and coral but the entire reef ecosystem. The importance of the Trapezia Pocillopora/Acropora Crab's role is now being recognized, and it is no longer considered a pest by hobbyists. Keeping this crab in your aquarium may improve your success with SPS husbandry as corals hosting Trapezia sp. have higher survival rates and stronger growth.