Littorina saxatilis has a plump shell, up to 18 mm in height and 14mm wide with a low spire of 4-5 whorls. The sculpture of the whorls are often V-shaped in section, with deep sutures. The aperture is large and rounded, with the outer lip everted slightly where it meets the columella. The colour of the shell is variable - yellowish white, greenish, reddish, brown - but usually has some pattern and a dark throat.Littorina saxatilis is a highly polymorphic species and there is disagreement about whether morphologically and genetically varied populations should be considered as sub-species or ecotypes. For a full review of littorinids in general, and a comprehensive discussion of past and current views on separating Littorina saxatilis into sub-species see Reid (1996). Reid (1996) also lists all previous synonyms for Littorina saxatilis. Littorina compressa and Littorina arcana are very similar in appearance to Littorina saxatilis. All three species occur together on rocky shores between the Barents Sea and southern Brittany, including the British Isles. See Reid (1996) for distinguishing features.