Abalone

Abalone is a common name for any small to very large marine gastropod mollusc in the family Haliotidae, which once contained six subgenera but now contains only one genus Haliotis. Other common names are ear shells, sea ears, and, now rarely, muttonfish or muttonshells in parts of Australia, ormer in the UK, perlemoen in South Africa, and pāua in New Zealand. The number of abalone species recognized worldwide ranges between 30 and 130 with over 230 species-level taxa described. The most comprehensive treatment of the family considers 56 species valid, with 18 additional subspecies. The shells of abalones have a low, open spiral structure, and are characterized by several open respiratory pores in a row near the shell's outer edge. The thick inner layer of the shell is composed of nacre, which in many species is highly iridescent, giving rise to a range of strong, changeable colors which make the shells attractive to humans as decorative objects, jewelry, and as a source of colorful mother-of-pearl.

Source: Wikipedia