The stone is modest in size, roughly 1.6 metres long and 0.8 metres wide, but across its surface are twelve cupmarks, shallow circular depressions ground or pecked into the rock by human hands, each no wider than about six centimetres. Cupmarks are among the most widespread and least understood features of prehistoric Europe. They appear on standing stones, on boulders, on outcrops just like this one, and despite more than a century of serious study, no consensus exists about what they meant or what purpose, ritual, practical, or astronomical, they may have served.

The rock outcrop at Ballinaclogh belongs to a tradition of cupmarked stone that extends across Ireland and Britain into the Neolithic and Bronze Age, roughly four to five thousand years ago, though individual examples are notoriously difficult to date without associated finds or features. What can be said with some confidence is that the act of making them was deliberate and repeated; twelve marks on a single outcrop suggests sustained attention to this particular surface, on this particular slope, for reasons now entirely opaque. The east-facing aspect may or may not be significant; some researchers have noted possible solar alignments at comparable sites, but that remains speculative.