This limpet is commonly found on rocks in the intertidal zone. It is an oblong shape, often narrowing slightly at one end, and is often distinctively eroded. It has several large radial ribs, and is usually dark-coloured in between, although colour and pattern can vary. It is similar to P. alticostata, which usually has a greater number of ribs, is less eroded and more often has a pattern of horizontal stripes between the ribs, although these characters can all vary.
