Any fish species in the family Ostraciidae (order Tetraodontiformes). Trunkfishes are encased in an triangular inflexible bony carapace which protects them from predators.Only the jaw, eyes, the bases of the fins, and the caudal fin protrude from this carapace They are slow swimmers that move primarily by sculling with their dorsal and anal fins and use their caudal fin for sudden bursts of speed. They are also known as boxfishes or cowfishes.