coat-of-mail chiton

Coat-of-mail chiton (Leptochiton asellus) is a small marine mollusc in the class Polyplacophora, family Leptochitonidae, found in cold waters of the northeastern Atlantic and North Sea, including the coasts of Norway, the United Kingdom, Ireland, France, and the Iberian Peninsula. It lives on rocky subtidal and shallow intertidal substrates, grazing on encrusting algae, diatoms, and organic detritus adhering to rock surfaces. Like all chitons, it has a distinctive dorsal shell composed of eight articulated plates surrounded by a muscular girdle, allowing it to curl into a ball when dislodged—a characteristic that has earned chitons the common name coat-of-mail. Leptochiton asellus is a small species, typically reaching only 10–20 millimetres, and is often found in aggregations beneath stones and boulders. It is assessed as Least Concern by the IUCN, with stable populations across suitable rocky intertidal and subtidal habitats throughout its range. Chitons as a class are ancient molluscs with fossil records extending to the Cambrian period, representing one of the most primitive lineages of shell-bearing invertebrates.