The often much eroded shell has an elongated low cone shape with the apex close to one end.

It is even more elongated, up to twenty-five millimetres long, and dark blue with concentric growth rings.

[3] It is most abundant in California and favours vertical rock faces in wave-swept areas in the upper littoral zone.

[1] The owl limpet is a territorial species and some individuals return to the same specific homesite every time the tide goes out.

The black oystercatcher, Haematopus bachmani is the only known predator of the owl limpet[6] but they are also harvested by humans for food.

Large competitors are dislodged by pushing them away with the anterior part of the shell, and if barnacles settle, they are rasped away with the radula.