Gyrolepis sp.

Ganoid scale of Gyrolepis, extinct genus of prehistoric actinopterygian (ray-finned) fish from the Middle-Upper Triassic era in what is now Europe.

Ganoid scales are hard and shiny, diamond-shaped, found in primitive fish such as sturgeons and gar. They are large plates that cover the body of the fish with a layer of hard enamel called ganoin, instead of the dentin and cosmine of the older cosmoid scales from which they are derived. These scales do not overlap like others, but rather fit together using peg-and-socket joints, forming armor that protects the fish from predators.