Most, if not all, crustaceans will molt, a process that shed and cast off the old exoskeleton. After molting, the crustacean will 1) get bigger 2) hungrier 3) replace lost limbs
The black one is the actual crab, the shell at this time is very soft. The browish one is only the old exoskeleton, notice how the eyes are empty. There are only 3 limbs excluding the claw on the left side of the exoskeleton and notice the different color of the new limb on the actual crab.
Soft on the bottom too. Don't worry, it's very alive, I just wanted to take a good photo.
The black one is the actual crab, the shell at this time is very soft. The browish one is only the old exoskeleton, notice how the eyes are empty. There are only 3 limbs excluding the claw on the left side of the exoskeleton and notice the different color of the new limb on the actual crab.
Soft on the bottom too. Don't worry, it's very alive, I just wanted to take a good photo.