Hermit crabs go through periods of highly sluggish activity, or even inactivity, referred to as molting. During molting, hermit crabs develop a new exoskeleton and shed their old exoskeleton.
The size of a particular hermit crab influences how many times it molts on a yearly basis. Large hermit crabs have only one period of molting in a year, while smaller hermit crabs can molt a few times per year, as they have a higher growth rate. Hermit crabs are 10-legged crustaceans, but four of the legs are hidden. As hermit crabs grow through molting, they need to accordingly adjust the size of the shell that they carry. While snail shells are some of the most common for a hermit crab to carry, the crabs have differing preferences.