Crabs moult through a process called ecdysis, which allows them to grow since their hard exoskeleton (shell) doesn’t stretch. Here's how it works step-by-step: Pre-molt stage: The crab absorbs calcium from its old shell and stores it in its body. It also starts forming a soft new shell underneath the old one. During this time, the crab may stop eating and hide to prepare for moulting. Shedding the old shell: The crab takes in water to swell its body, which causes the old shell to crack—usually a