A granite boulder sitting in a field in Ballybought, County Kildare, has spent centuries collecting rainwater in a shallow circular basin worn into its upper surface. That basin, roughly 46 centimetres across and almost perfectly round, is what makes it a bullaun stone, a category of ancient carved or worn rock found across Ireland, typically associated with early Christian and pre-Christian ritual use. This particular example is known locally as the wart stone, a name that places it in a well-documented folk tradition whereby water gathered in such basins was believed to cure skin complaints. The sufferer would rub the water onto the wart, sometimes accompanied by a spoken charm or a circuit of the stone, and the cure was expected to follow.

The stone itself is a low, broad granite boulder, measuring 1.4 metres in length and 1.2 metres wide, rising less than half a metre from the ground. It sits on a gentle west-facing slope in what is now improved pasture, the kind of agricultural land that has been drained, reseeded, and otherwise tidied into productivity, which makes the survival of the stone all the more notable. Bullaun stones were not always respected during land improvement schemes, and many have been moved, broken, or buried. This one has remained in place, still gathering water, still carrying its local name.