This ancient carved stone, located at Carrowreagh Or Craignacally, was first identified by researcher M.A.M. Van Hoek in 1987 during his comprehensive survey of Donegal's prehistoric art. The rock outcrop, which slopes gently at 13 degrees towards the east-northeast, sits close to both the minor road and the northern fence of the field, making it relatively accessible for those who know where to look.

The artwork consists of four cup marks carved into the stone surface, circular depressions that were painstakingly pecked out by our prehistoric ancestors thousands of years ago. What makes this particular example especially intriguing is that one of the cup marks features a surrounding ring, though centuries of Irish weather have heavily eroded its northern section. Van Hoek also noted what appears to be an uncertain 'tail' extending from this ringed cup mark, though its exact purpose or meaning remains a mystery.

Cup and ring marks like these are found throughout Ireland, Scotland, and northern England, representing one of the most enigmatic forms of prehistoric art in these islands. Dating typically from the Neolithic to the Early Bronze Age (roughly 3800 to 1500 BCE), their exact purpose continues to elude archaeologists. Some theories suggest they served ritual or ceremonial functions, whilst others propose they may have been territorial markers or even primitive maps. The Ballyduff example, with its combination of simple cups and the more elaborate ringed design, adds another piece to this enduring archaeological puzzle.