Chitin
Chitin is a derivative of glucose, and a primary component of cell walls in fungi, the exoskeletons of arthropods, such as crustaceans and insects, the radulae of molluscs, cephalopod beaks, and the scales of fish and lissamphibians. It is used in agriculture and in several industrial processes, including the formation of edible films and as an additive to thicken and stabilise foods.