The crustaceans exhibited at the Marché aux Poissons (Fish Market) of Trouville-sur-Mer are arthropods with a more or less rigid body covered with a low-stretch chitinoprotein exoskeleton called the cuticle. Their growth, therefore, happens through successive molts. Certain areas of their body remain flexible to allow the articulation of the different segments, all equipped with a pair of appendages, and to enable the animal's movements. Secreted by the epidermis, the cuticle has a high content of chitin which becomes impregnated with calcareous salts and contains pigments of various colors.