A rigid box with horns, hovering over the sand on almost invisible fins.
A boxfish to about 46 cm, yellow to olive with pale blue-centred spots, the body enclosed in a rigid triangular carapace of fused bony plates with a long forward horn above each eye and a second pair projecting backwards from the lower rear corners. The carapace does not flex, so all propulsion comes from the small fins, and the fish moves in a slow hover that looks like a mistake. Juveniles are almost spherical, bright yellow and heavily spotted.
Feeds by blowing jets of water into sand to expose small invertebrates, leaving small craters, and by picking at algae and benthic growth. The armour makes it slow but hard to eat, and it has a second defence: like other boxfish it can release a toxin, ostracitoxin, from the skin when severely stressed — a real effect, mostly documented in confinement rather than in the sea, and not something a diver will trigger. Recorded from the shallows to about 40 m. It drifts away rather than fleeing, so a slow parallel approach works where a direct one does not.
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.