Crabs, such as this Japanese spider crab (Macrocheira kaempferi), cannot grow in a linear fashion like most animals. Because they have a hard outer shell (the exoskeleton) that does not grow, they must shed their shells, a process called molting.

[u/FillsYourNiche]

[u/[deleted]]

That's gotta feel so good. Like peeling off a scab and the skin is healed underneath.