.Pleuroploca gigantea, common name is the horse conch. The official state shell of Florida, the horse conch is an extremely large specel captiva islandies of extremely predatory subtropical and tropical sea snails, a marine gastropod mollusk in the family Fasciolariidae, the spindle snails, tulip snails and their allies. This species is the largest snail in the Americas, and one of the largest univalves in the world. Also known as the giant band shell, young horse conchs have orange-colored shells; adults have orange apertures. They can grow up to 24 inches long.