The hermit crab has soft abdomen which they protects by using abandoned shell as their shelter. The shell is never a part of the hermit crabs but it is worn by them to protect themselves. The Blue Leg Hermit Crab has the extended abdomen and they spiral up themselves in it and expose only the head and its claws. When they are sensitized by any predator, they coil up inside the shell and seek for protection. The hermit crabs undergo molting process where they shed their exoskeleton in order to obtain a new one, during that time they use the abandoned shell as their shelter. A hermit crab chooses its shell according to the size of its opening. Then it reaches down inside a prospective shell using large claw to make sure that it is the correct size. After thoroughly checking out the shell properly, it rolls the shell around to make sure that nothing else is living inside and also to empty out any living possible debris. And then finally it resides itself in it by positioning its body accordingly. These shells are ornamental and can be used in decorative way in any home tank. Also, its presence will reduce the likelihood of the hermit crabs within the aquarium competing for a home.