Callus (mollusc)

A callus is an anatomical feature that exists in some mollusk shells, a thickened area of shell material that can partly or completely cover the umbilicus, or can be located as a coating on the body whorl near the aperture of the shell (i.e. a parietal callus or columellar callus). A callus exists in the shells of various species of gastropods (snails) and also in the shells of several species of Nautilus, a cephalopod.

Callus (mollusc)

A callus is an anatomical feature that exists in some mollusk shells, a thickened area of shell material that can partly or completely cover the umbilicus, or can be located as a coating on the body whorl near the aperture of the shell (i.e. a parietal callus or columellar callus). A callus exists in the shells of various species of gastropods (snails) and also in the shells of several species of Nautilus, a cephalopod.