At just 0.8 metres high and roughly 0.42 by 0.37 metres at its base, it is a modest presence in the landscape, rectangular in profile and oriented roughly west-northwest to east-southeast. What makes it quietly remarkable is not the stone itself but its company: four separate examples of rock art have been recorded in its immediate vicinity, clusters of carved marks incised into exposed stone surfaces, a form of prehistoric expression found across Atlantic Europe and concentrated heavily in the uplands of Kerry and Cork.

The convergence of a gallaun and multiple rock art sites in one small area at the valley head suggests this was a place that held some significance during prehistory, though the exact nature of that significance remains opaque. Rock art of this kind, which typically takes the form of cup marks, rings, and abstract motifs pecked into the rock surface, is notoriously difficult to date with precision, but in Ireland it is generally associated with the Later Neolithic and Bronze Age periods. The Iveragh Peninsula, on which Derreeny sits, has a remarkable density of such sites, something that A. O'Sullivan and J. Sheehan documented at length in their 1996 archaeological survey of south Kerry published by Cork University Press. Whether the gallaun and the rock art panels were created at the same time or accumulated meaning across generations is an open question, but their proximity is not likely accidental.