MOLTING

Crustacean shells are natural sources of chitin as they consist of (20–30%) chitin, (30–40%) proteins, (30–50%) calcium carbonate and the rest pigments (astaxanthin, canthaxanthin, lutein or β-carotene). The proportions of these constituents are dependent on the species and season in which the animal exists.. In skeletal tissue, chitin combines with protein to form protein-chitin matrix calcified to produce hard shells. The shells may also contain lipids from the muscle residues and carotenoids of astaxanthin and its esters. /

Full Length Article:
Acetylation, crystalline and morphological properties of structural polysaccharide from shrimp exoskeleton – Engineering Science and Technology, an International Journal
Volume 20, Issue 3, June 2017, Pages 1155-1165

Since the shrimps’ shell cannot grow with the creature, as with all crustaceans, they must shed their skin regularly. Many shrimp-keepers have been shocked to find the shell shed in this process, called the exuvia, in the aquarium. Since the whole shell is shed, the exuviae
are sometimes mistaken for dead creatures. But thanks to their transparent colour, they can easily be differentiated from dead specimens. Exuviae need not be removed from the aquarium; they are partly consumed by the creatures themselves, the rest is rapidly decomposed by the micro-organisms in the tank