Theodoxus concavus gastropod mollusc collected from the Oligocene Headon Beds of Headon Hill, Isle of Wight. These small water snails live on rocks and feed on algal covers. They are small gastropods with globular shaped shells; these specimens measure between 6 and 8 mm. They are in good condition and would make a welcome addition to any collection. The Headon Beds in which these gastropods were found are comprised of freshwater, brackish and marine deposits but it is brackish and freshwater environments which theodoxus gastropods favour. Each specimen is supplied in a small plastic bag with an information label.