One of the few animals that eats crown-of-thorns, and heavily collected for its shell.
The largest gastropod a diver is likely to meet in the region, with a heavy spindle-shaped shell to about 40 cm and occasionally half a metre, drawn out into a tall spire and glossy rather than sculptured. The shell is cream to fawn, marked with crescent and chevron-shaped brown to orange-brown blotches arranged in spiral bands, and the long aperture is orange inside with white ridges across the inner lip. The animal itself is mottled cream and dark brown, with eyes at the base of the tentacles and a long extensible siphon held out in front. The frog shells and the smaller tritons that share the same ground are warty, sculptured and covered in a bristly outer skin, none of which this species has.
It is a predator on echinoderms. It locates sea stars and sea cucumbers by scent, holds the prey with the foot and rasps into it, and it is one of the few animals that will take the crown-of-thorns starfish Acanthaster planci. That relationship is part of the long argument about crown-of-thorns outbreaks: tritons have been collected for the shell trade across the region for so long that the natural density of the species at most sites is not known, which is the difficulty with settling the question either way.
Mostly nocturnal, under ledges and in rubble by day and moving over sand and reef at night. Recorded from the shallows to about 30 m. It is protected in some countries in the region and taken freely in others, and most divers see the shell in a market before they see the animal.
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.