A shell with six curved spines, and an animal that hops on a claw instead of gliding.
A large sand snail whose flared outer lip is drawn out into six long, hollow, curved spines, with a seventh forming the siphonal canal at the front. The shell reaches about 25 cm including the spines, is cream to grey with brown mottling outside and is usually overgrown or encrusted, while the aperture inside is smooth and glossy in orange, pink or violet. The contrast between the dull exterior and the polished interior is the quickest identification. Females grow larger and have longer, more strongly curved spines than males. Lambis chiragra, which occurs on the same ground, has much stouter, blunter spines and a heavier shell.
The animal does not glide as most snails do. The foot is narrow and ends in a hard, curved, claw-like operculum, which it plants in the sand and uses to lever the whole shell forward in a series of hops; the same claw rights the animal if it is turned over. The eyes are good ones, each on a long stalk with a small tentacle beside it, and they are usually the first part of the living animal to appear from under the lip.
It grazes algae and detritus on sand, rubble and seagrass, is often half-buried with only the spines showing, and is recorded from the shallows to about 20 m. It is taken for food and for the shell trade throughout the region, and empty shells on a slope are more common than living animals.
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.