Triplofusus giganteus, previously known as Pleuroploca gigantea, common name the Florida horse conch, is a species of extremely large predatory subtropical and tropical sea snail, a marine gastropod mollusc in the family Fasciolariidae, the spindle snails, tulip snails and their allies. Although known as a horse conch, this is not a true conch, as it is not in the family Strombidae. This species is the largest gastropod in the American waters, and one of the largest univalves in the world.