Measuring roughly 4.7 metres north to south and 3.8 metres east to west, the stone was at some point earmarked for quarrying: the entire western face is covered in a series of drilled holes, the tell-tale preparation for splitting a boulder apart using plug-and-feather technique, where iron wedges are driven into a line of drilled sockets until the rock cracks along a controlled fracture. The work was never finished, and the stone remained whole.

What makes that near-miss particularly significant is what covers the boulder's high central ridge: around twenty cup marks, the simplest and most widespread form of prehistoric rock art in Ireland and Britain. Cup marks are shallow circular depressions pecked or ground into stone surfaces, typically a few centimetres across and rarely more than a centimetre deep. Their purpose remains genuinely unclear, and that uncertainty is part of what makes them compelling. On this boulder the cups average between four and six centimetres in diameter and around a centimetre in depth, though one outlier on the ridge reaches twelve centimetres across and two centimetres deep, considerably larger than the rest. The marks are weathered, suggesting considerable age, though erratic boulders, large stones deposited by glacial movement far from their geological origin, have a way of resisting easy dating. The carving was done at some point after the ice left the stone here; when exactly, nobody can say.