Juveniles, unlike adults, have spirally grooved shells and thin translucent body whorls which show the exterior markings within the aperture. The pure white columella (no tint of any other colour), often with a dark brown mark basally, differentiates L. littorea at all sizes from others in the genus in Britain and N,W. Europe.
Found in empty barnacle cases, Menai strait, Wales. March 2011.