Spiny Oyster most commonly comes in orange, red, and purple. Although very rare it can be found in a yellow hue too. Their colors are based on what the mollusks eat and the depth of water/temperature where they live. One can distinguish the shell from the commonly confused coral by the white variation found throughout. Spiny Oysters are found throughout the world in warm tropical waters. The majority of Spiny Oyster used in Native American jewelry comes from the Sea of Cortez (Gulf of California) on the Baja Peninsula. There are over 70 species of Spiny Oyster found thoughout the world. The two species most commonly used in Native American Jewelry are Spondylus Princeps and Spondylus Calcifer. Spondylus Princeps are primarly coral red and orange. They can be found in 15- 50mm deep waters and they favor sandy areas.Spondylus Calcifer is most commonly used. They are orange and purple in color with red banding along the edges. Their spines are shorter but grows to be thicker and larger than the Princeps species. They favor rocky formations and often attach themselves to the rocks. Spiny Oyster is more closely related to mussels. They are also known as thorny oyster or scientifically bivalve mollusks. Spiny Oyster is still harvested by hand by divers. It is believed that the spines may have evolved to attract other organisms to settle on the shell to conceal it from predators. Spiny Oyster has been used by Native Americans since pre-historic times, unlike red coral which was harvested in the Mediterranean and introduced by Europeans.