Lottia instabilis is a species of sea snail, a true limpet, a marine gastropod mollusk in the family Lottiidae.

The shell of Lottia instabilis is specially adapted by the shape of its rim to adhere to the holdfasts and stipes of kelp.

[3] Native to the northeastern Pacific Ocean, L. instabilis is present from Kodiak Island, off the coast of Alaska, to San Diego, California.

[2] It also occurs on bare rock and sometimes on the shells of gastropod mollusks, including those occupied by hermit crabs.

[3] L. instabilis is a herbivore and feeds directly on kelps such as Saccharina dentigera[4] and Pterygophora californica.