The creature in the centre of this photo is a Chiton.
Chitons are considered to be very primitive molluscs. They are a very distinctive group because their protective armour consists of eight separate, usually overlapping, plates or valves held in position by an encircling muscular girdle.
The girdle is often marked with unusual spikes and spines. Chitons are long (elongate), usually flattened, and symmetrical.
They have a very muscular foot, and when disturbed, can clamp down so that they cannot be dislodged unless their shell is smashed. Chitons can live for one to twenty years, or more.
