Onchidoris muricata usual maximum length 14 mm. Usually, no dark pigment marks on dorsal surface. Lamellae on rhinophores more closely spaced than on O. sparsa. Tubercles shaped as club with flat/slightly rounded tip. Spawn a spiral of two or three coils on a wide variety of encrusting bryozoans including Membranipora membranacea and Securiflustra securifrons. Length 8 mm. Menai Strait, Wales, March 2012.