Left and right sides of a specimen removed from its shell.
1: side of dorsal surface of foot.
2: sole of foot.
3: operculum.
4: neck lobe.
5: extension of eye-tentacle extending round base of cephalic tentacle.
6: edge of white translucent mantle, partly pulled back from mantle cavity.
7: ctenidium inside mantle cavity.
8: tip of ctenidium protruding from folded back mantle.
9: epipodial tentacles and black sensory papillae.
10: position of very large uroginital papilla in females. This specimen is a male with its much smaller papilla hidden further back in the mantle cavity. Females lay about 100 ova, each of which has a gelatinous coat, and all are embedded in a mucous mass secreted by a gland in the papilla.
11: columellar muscle; attached to columella (central column of shell), contracts to pull body into the shell.
12: tip of viscera missing.

marinvert.senckenberg.science/image-browse/