A ribbed sand snail with a foot far larger than its shell, hunting crabs after dark.
A snail with a shell to about 8 cm, cream to pink, crossed by widely spaced sharp axial ribs that give the group its name and marked between them with brown chevrons and bands. The foot is much larger than the shell and cannot be drawn fully inside it; extended, it is broad, pale and mottled, and it covers most of the shell as the animal moves.
It hunts on open sand at night and it takes crabs. The recorded method is to throw the front of the foot over the prey and pin it in a mass of sand bound with mucus, which holds the crab still while it is eaten. Attacked, the snail can shed the rear part of the foot and leave it behind, and the wound closes over.
By day it lies buried, and the only sign of it is a shallow trail across the sand. Recorded from about 3 to 25 m.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.