The coat-of-mail shells (aka chitons)

Chitons is the common name for the species of the Polyplacophora (Class) shells. Polyplacophora is seems to mean at Greek "the ones who have a lot of plates". The shell is composed from a lot of plates so the animal is more flexible to his movement. The first photo is from Chiton olivaceus which probably take his name from his colour which is similar to the olive. The second photo is the specie Lepidopleurus cajetanus and the photo taken as I moved a rock at shallow water. Both pictures was taken at Paros island in shallow water. More information about Chitons behaviour you can find in the following link.

Chitons: Polyplacophora - Behavior And Reproduction