For as long as abalone have been nourishing human appetites, their mother-of-pearl bearing shells have been used in ritual ceremonies to replenish our souls as well. Abalone are a type of mollusk, like clams and oysters, except inside their flat, one-sided, ear-shaped shells, abalone have tentacles and feet. These sea snails cling to rocks near to shore, and are often consumed by other marine species. The shell of abalone is extremely durable. Microscopic calcium carbonate stack like bricks stuck together by a layer of protein. The protein absorbs blows to the shell, while the brick formation of the calcium carbonate keeps the shells from shattering. Animals like otters have to get creative when harvesting abalone. Otters have learned to use rocks to pry the muscular mollusks from their tidal homes and scoop them out of their shells. Many native cultures have sustained themselves for centuries by consuming raw and cooked abalone. Tribes native to the North American west coast used abalone shells as currency. Today in South Africa, abalone is still highly sought after, and their shells, which are known to have an especially colorful iridescence, are very valuable. While the North American west coast and South Africa are the two main sources for abalone, they can also be found along the coasts of New Zealand, Australia and Japan.