Cup marks are among the oldest forms of rock art found across Ireland and Britain, their precise meaning unresolved after generations of study. They appear on standing stones, burial monuments, and exposed rock faces, sometimes in dense clusters, sometimes, as here, alone.

This particular stone is modest in scale, measuring roughly 0.4 metres long, 0.3 metres wide, and just 0.04 metres thick, more a flat slab than a dramatic monolith. It now forms part of the wall at the base of a cairn, which is a mound of stones typically associated with prehistoric burial or ritual activity, on Keadeen's summit. Whether the boulder was always part of that structure or was incorporated into it at a later point is not clear. What is certain is that it sits immediately north of the summit, in a position that commands what are described as very extensive views across the surrounding landscape, the kind of elevated, exposed spot that recurs again and again in the placement of prehistoric monuments throughout Ireland.