Pachygrapsus marmoratus is a small crab of 3 to 4 cm with an almost square carapace marbled in green, brown and bronze. It lives in the intertidal zone on rocks, sheltering in crevices. Extremely fast and agile, it sometimes jumps out of water to escape a predator. Omnivorous, it feeds on algae and debris. An iconic species of Mediterranean and Atlantic coasts.

