Abalone

Most abalone vary in size from 20 mm (0.8 in) (Haliotis pulcherrima) to 200 mm (8 in). The largest species, Haliotis rufescens, reaches 300 mm (12 in).

The shells of abalone 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 ornaments, jewelry, and as a source of colorful mother-of-pearl.

The haliotid family has a worldwide distribution, along the coastal waters of every continent, except the Pacific coast of South America, the Atlantic coast of North America, the Arctic, and Antarctica. The majority of abalone species are found in cold waters, such as off the coasts of New Zealand, South Africa, Australia, Western North America, and Japan.

Abalone have been harvested for seafood and aesthetics since prehistory. Abalone shells and associated materials, like their claw-like pearls and nacre, have been used as jewelry and for buttons, buckles and inlay. These shells have been found in archaeological sites around the world, ranging from 100,000-year-old deposits at Blombos Cave in South Africa to historic Chinese abalone middens on California's Northern Channel Islands. For at least 12,000 years, abalone were harvested to such an extent around the Channel Islands that shells in the area decreased in size four thousand years ago.