Ostracioidea

The Ostracioidea, commonly known as boxfish or trunkfish, are a small group of shallow-water marine fishes belonging to the family Ostraciontidae. These fish are distinguished by a hard, boxlike carapace that covers most of their body, providing protection. This carapace is formed from fused bony plates and can vary in shape, appearing triangular, square, or pentagonal in cross-section depending on the species.12

Boxfish are often brightly colored and are found in warm and tropical seas worldwide. While generally considered good to eat, they can exude a toxic substance when handled, which can be harmful to other fish if they are kept together. Some species also have horn-like projections on their heads, leading to the alternative name "cowfish". The largest boxfish can grow up to about 50 cm (20 inches) in length.2