The decorated area measures just sixteen centimetres across, and the carving itself, a central cup surrounded by two concentric rings, is modest almost to the point of invisibility. Yet the care involved is apparent: the inner ring, two centimetres wide and two millimetres deep, and the outer ring, slightly narrower at one and a half centimetres, were both worked by hand into the fractured sandstone face. The rings are penannular, meaning they stop just short of being fully closed, running from the south-east, around through west and north, to the north-east, leaving a deliberate gap.

Cup-and-ring marks are among the most widespread and least understood forms of prehistoric art found across Ireland and Britain, typically dated to the Neolithic or Bronze Age. Why certain rocks were chosen, what the symbols meant, and who made them remains genuinely unresolved. At Derrynablaha, the carved face looks southward from a position at 173 metres above sea level, just below a change in slope on a south-east facing hillside. The rock itself, roughly 2.5 metres tall and cut into the hillslope on its western side, overlooks the Kealduff river valley, with Lough Brin visible to the east. A second example of rock art lies approximately fifty metres to the north-west, suggesting this was not an isolated act but part of a wider pattern of marking this particular landscape. Closer still, a deserted clachan, the remains of a small informal cluster of dwellings, sits about fifty-five metres to the west-north-west, and an abandoned farmhouse stands roughly forty metres to the east. The prehistoric carving and the post-medieval abandonment occupy the same hillside, separated by millennia but sharing the same unremarkable view.