Set into a gentle bank-like rise in the landscape, the stone is earth-fast, meaning it is fixed in the ground rather than free-standing, and on its smooth upper surface someone, at some point in prehistory, pecked out a single oval cupmark. Cupmarks are among the most common forms of prehistoric rock art found across Ireland and Britain: shallow, cup-shaped depressions ground or hammered into stone surfaces, their precise purpose still debated. This one measures roughly eight centimetres at its longest and six centimetres across, with a depth of about one and a half centimetres, and pock marks are still visible in the base of the hollow, traces of the repeated blows that created it.

What makes this particular example a little more involved than a simple depression is the presence of two shallow lines extending from either side of the cupmark, one running to the north-east for about seven centimetres, the other to the south-west for six centimetres. Whether these lines were intentional extensions of the design or served some separate purpose is not recorded. Immediately to the north-west of the cupmark there is also a natural fissure running in roughly the same north-east to south-west direction, which raises the question of whether whoever carved the mark was responding to, or working in dialogue with, a feature already present in the stone. The rock art sits approximately one and a half metres from a cairn, a mound of stones that may itself be a prehistoric burial monument, suggesting this small corner of the island carried some significance to the people who shaped it. The site is documented by Gosling, Manning and Waddell in their 2007 survey of Clare Island.