A small polished crab shaped like a water-worn stone, half-buried on open sand.
A small crab with a hard, smooth, strongly domed carapace, to about 3 cm, usually white, cream or pale grey and sometimes finely speckled. The shape is the point: rounded, polished and evenly convex, so that an animal sitting on open sand reads as a pebble and is passed over. The front narrows to a short blunt beak, the eyes are small, and the chelipeds are long, slender and folded neatly back against the front of the body when the animal is at rest.
The walking legs are short and are used to back down into the sediment rather than to run. A disturbed animal moves a short distance, tips backwards and works itself under the surface in a few seconds, leaving a slight mound and nothing else. The mouthparts and the front of the carapace form a channel that carries water to the gills while the animal is buried, which is what allows it to stay down.
They occur on open sand and silt, in the shallows and well down a slope, and are most often found at night when more of them are out on the surface. Genera on this ground include Leucosia. Species are separated on the granulation of the carapace and the shape of the front. Recorded from about 3 to 30 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.
