20 Patella pellucida. Length about 15mm. Growth Stage 5 frond dweller (GS5f). March 2010. Menai Strait, Wales. © D. Evans.

20 Patella pellucida. Length about 15mm. Growth Stage 5 frond dweller (GS5f). March 2010. Menai Strait, Wales. © D. Evans.

Late adult, Growth Stage 5f, on Laminaria frond. Shell is a high conoid, steeper at the anterior, resembling a Phrygian cap. The posterior is a long smooth convex curve; the anterior is a shorter and steeper concave curve. Exterior surface smooth, usually with no epibiotic growth or, in this case, a little.
Concise
Part 1, SHELL FORMS: 02 Patella pellucida. Growth Stage 2 (GS2). July 2012. Littoral. North Yorkshire, England. © P. Lightfoot.
Part 2, BODY & ANATOMY: 03 Patella pellucida. Growth Stage 3 (GS3). 2009. Sublittoral, Farne Islands, Northumberland, England. © P.Lightfoot.
Part, 3 HABITS & ECOLOGY: 04 Patella pellucida. Length 4.6mm. Growth Stage 3 (GS3). September 2016. Yorkshire, England. © P.Lightfoot.