Millerostaeus minor dorsal plate fossil preserved on a silty mudstone matrix, collected from the Devonian Old Red Sandstone deposits of Rousay, Orkney. During the Devonian period, the area of Orkney was occupied by an extensive fresh water lake - Lake Orcadie. Rivers from nearby mountains provided the lake with fresh water and nutrients allowing for an abundance of diverse fish life to become established around the shallow lake margin. Upon death some fish fell to the deep, oxygen starved lake bed where they would become incorporated into the sediment permitting their preservation. This dorsal plate of Millerostaeus is just one of the many fish remains which can be found in the Devonian Orkney sediments. The plate measures 2.5 cm in length and is supplied in a small plastic bag with an information label.