Fissurella nodosa

Fissurella nodosa, commonly known as the knobbed keyhole limpet, is a species of sea snail, a marine gastropod mollusk in the family Fissurellidae, the keyhole limpets.

Description
The size of an adult shell varies between 20 mm and 44 mm.

Distribution
F. nodosa is endemic to the Florida Keys, the Gulf of Mexico, the Caribbean Sea and the West Indies.