Crustaceans may pass through a number of
larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a
moult, in which the hard
exoskeleton is shed to allow the animal to grow. The
larvae of
crustaceans often bear little resemblance to the adult, and there are still cases where it is not known what larvae will grow into what adults. This is especially true of crustaceans which live as benthic adults (on the sea bed), more so than where the larvae are
planktonic and therefore more easily caught.