A pair of overlapping, muscular flaps extending from the mantle which are held tightly together to produce a short and flexible tube. Only present among the living cephalopods, and used to direct the jet of water expelled from the mantle cavity. Often called the 'funneP. Lappets Lateral extensions of the shell on either side of the aperture. These are generally found in the microconch only, and may have served as markers of sexual maturity and virility, similar to the peacock's tail. Lobe The posterior-pointing folds in the septum where it meets the inner surface of the shell. An important part of the suture line and used in classifying ammonites.

The hyponome is the organ used by cephalopods for locomotion. It is a muscular funnel or siphon into which water is drawn. The hyponome expands and then contracts, sending a jet of water rushing out.