Chitin is the main component in this supportive outer covering of lobsters & insects
It is a 
characteristic component of the cell walls of fungi, the exoskeletons of ... crabs, 
lobsters and shrimps) and insects, the radulae of molluscs, and the beaks and 
internal shells... [DOC] [TLE] Exoskeleton - Wikipedia [PAR] Chitin forms the exoskeleton in arthropods including insects, arachnids such as 
spiders, crustaceans such as crabs and lobsters, and in some fungi and bacteria.