An armoured mollusc built like nothing else on the shore: eight overlapping shell plates run down the back in a row, hinged so the animal can flex over uneven rock or roll into a ball if pried loose. Around them runs a thick leathery girdle studded with short bristles and spines. Color is dull gray-brown to blackish, usually eroded and overgrown with algae, so the outline matters more than the pattern. Length reaches about 50 mm (2 in), making it the largest chiton on these shores.
It lives clamped to bare rock in the surf and splash zone, where few other molluscs hold on, and grips with a broad muscular foot strong enough that a knife blade will break the plates before the animal lets go. Feeding happens at night: the chiton crawls out to rasp algal film from the rock with a radula hardened with magnetite, then returns before dawn to the same resting scar, a shallow depression its own shell has worn into the stone. Along 🌊 Red Sea shorelines it is one of the most reliable finds on rocky headlands at low tide, though divers almost never meet it - the animal lives above the water more often than below it.
- eight overlapping plates in a row down the back
- thick girdle around the edge, bristled with short spines
- clamped hard to bare rock in the splash zone
