An exoskeleton is hard encasement deposited on the surface of an animal. The cuticle is a jointed exoskeleton of the arthropods. The cuticle can be flexible or hard depending on the function of the cuticle at that location. As the animal grows, it enlarges the shell by adding to its outer edge. During growth spurts, however, the arthropod must shed its exoskeleton and make a larger one.