Family: Cassidae. The Helmet family includes bonnets, false tuns, and true helmets. They number around 60 species worldwide. The larger Helmets feed on members of the sea urchin family. The helmet creature uses its radular teeth and acidic secretions to drill a hole into the shell of the urchin and digest the soft parts within. They live in shallow waters, with most of the shell buried below the surface of the sand. The larger helmets build a shield to help them glide along the sandy sea bottom. Interesting Facts: Helmet shells have been used since the Roman Empire for everything from food to cooking pots, trumpets, and jewelry. Most cameos are made from the Bullmouth helmet shell Cypraecassis rufa. This shell which is native to East Africa is shipped to Italy for carving into cameos. Julius Caesar presented Cleopatra with a cameo shell as a sign of his affection for the Egyptian Queen.