SQUID, OCTOPUS, and CUTTLEFISH. However, only the nautilus has a shell. The young animal's tiny horn-shaped shell grows into a flat spiral shape. The nautilus lives only in the front part of the shell. As it grows and adds more shell, it seals off the outgrown part of the shell. This is why the nautilus shell is described as having many chambers or rooms. Old tales tell of this beautiful and buoyant shell which supposedly sailed upon the surface of the South Seas.
Full-grown, it is the size of a man's fist and the shell is about six inches in diameter. It has nearly one hundred tentacles used for movement and for obtaining food. Two tentacles are smelling organs. Like other cephalopods, the nautilus pushes itself backwards by ejecting water.