Mithraculus sculptus also known as the emerald crab are some of our top clean up crew. This species is an omnivore and great scavenger feeding on nuisance algae( green hair algae or occasionally bubble algae) and decaying food that has fallen to the bottom. Best to keep this species in  a tank with plenty of food to insure it doesn’t starve and hunt for food elsewhere and stays peaceful in your reef with other inhabitants. Originally from the Caribbean and Gulf of Mexico and have a lifespan of roughly 2-4 years. Like most inverts these crabs will molt as they grow so they can disappear for a week or so while their shell hardens. Their molt is easily mistaken for a dead body but if you flip it over you can check to see if it is hollow. The shell then provides minerals and nourishment for the crab or other tank mates.