P.vulgata return to their home scars after feeding excursions. The shell closely fits the surface because the limpet grinds the rim against the substrate to erode it to fit the contours of hard rock or to form a pit in soft rock.  Pits often have a raised central area (1) where the foot attaches and a surrounding recessed area (2) cut by the shell rim. Soft Devonian sandstone, Orkney, Scotland.