These are cup marks, among the most enigmatic forms of prehistoric rock art found across Ireland and Britain. Their purpose remains genuinely unknown. Ritual, territorial, astronomical, or simply symbolic, nobody has settled the question, and the stone at Farrankeal offers no obvious clues beyond the marks themselves.

The stone stands 1.63 metres high and is subrectangular in plan, its long axis running north to south, set in level pasture with a westward view over the Blackwater valley. That orientation is worth noting: the cup-marked face looks directly out over the valley, which may or may not be coincidence. What is curious is that the stone does not appear on the Ordnance Survey six-inch maps of either 1842 or 1904, meaning it went unrecorded by the principal mapping exercises of the nineteenth and early twentieth centuries, despite almost certainly having stood there for several thousand years. Whether it was simply overlooked, hidden by vegetation, or regarded as an unremarkable field feature at the time, the omission gives the site a slightly overlooked quality that the maps themselves seem to confirm.