Lined Top Shell

Phorcus lineatus

Phorcus lineatus is a sea snail characterized by its thick, solid shell that ranges in size from 10 mm to 35 mm. The shell has a globose-conic shape and is marked with numerous fine, zigzag, purplish-black lines on a dull grayish background. The spire is conic, with 6 to 7 convex whorls, and the apex is typically eroded and orange-colored. This species can be distinguished from Phorcus turbinatus by its more convex spire outlines and the position of the columella projection, which is nearer the base in P. lineatus. The base of the shell is often eroded in front of the aperture, which is oblique in shape. Lined Top Shells are found in the eastern North Atlantic Ocean, particularly in European waters, including the Portuguese and Spanish Exclusive Economic Zones, as well as the United Kingdom. They inhabit shallow waters, with all recorded occurrences being shallower than 40 meters, and 90% found at depths less than 10 meters. Their preferred habitats include rocky substrates where they can graze on algae. Breeding habits are not specifically detailed in the sources, but like many marine gastropods, they are likely to have a reproductive strategy involving external fertilization. Encountering a Lined Top Shell while diving may involve observing them clinging to rocks or substrates, showcasing their unique shell patterns.