Boxer Crab a Model Critter

Lybia (common names include boxer crabs, boxing crabs and, pom-pom crabs) is a genus of small crabs, including Lybia tesselata and Lybia edmondsoni. They are notable for their mutualism with sea anemones which grow on their claws for defense. In return, the anemones find new places to eat and mate. Boxer crabs use at least three different species of anemones, including Bundeopsis sp. and Triactis producta. The bonding with the anemone is not required for survival, however, and boxer crabs have frequently been known to live without them, sometimes substituting other organisms such as sponges and
corals. (Wiki)