Hemimarginula pumila, the pygmy ermarginula, is a species of sea snail, a marine gastropod mollusk in the family Fissurellidae, the keyhole limpets.

[1][2] The whitish to pale brownish conical shell is 6 to 13 mm long on a broadly oval base with an irregularly scalloped margin.

There are about twelve broad ribs that are minutely scabrous.

These ribs are crossed by three buff, radiating bands.

This keyhole limpet is fairly common and can be found on or under rocks in tide pools, shallow water and in the intertidal to the sublittoral zone (from 2m to 27 m deep) along the coasts of Southeastern Florida south to Brazil.