Gyroptychius milleri operculum or the gill cover of an extinct Devonian lobe finned fish, collected in Orkney. Gryoptychius are an extinct species of lobed finned fish from the Devonian period. They had a powerful elongated body, approximately 30 cm long and all of its fins except the pectorals were positioned in the lower end of its body to maximise tail power and aid in propelling the fish when swimming. Gyroptychius has been recognized as having particularity short jaws which would have provided a greater bite force. Each individual operculum is 2 cm in length and is preserved within a mudstone matrix, supplied within a small plastic bag with an information label.