A box crab with a domed shell whose rear corners are drawn out into two points, and claws so shaped that they fold flat across the front and close the animal into a smooth box - the posture that names the group and leaves no soft part exposed. Width reaches about 7 cm (3 in).
It spends the day buried in sand with only the eyes showing and hunts at night, and the right claw carries a tooth used as a tin-opener: the crab grips a snail shell and peels the whorls away in a spiral until the animal inside can be reached. Empty shells cut in that pattern are a reliable sign one is working the area even when the crab itself is out of sight. Sandy bottoms beside reef are the place to look, on a night dive, at the base of the slope where shells accumulate.
- domed shell with winged rear corners, drawn out into points
- claws fold flat across the front like shutters
- buried in sand with only the eyes exposed
- width up to 7 cm
