This is a bullaun stone, a type of rounded boulder bearing one or more cup-shaped depressions that appear at early Christian sites across Ireland. Their precise function remains debated; holy water, votive offerings, and grain grinding have all been proposed, and many bullauns became associated with healing traditions and cursing rituals that long outlasted the medieval period.

The stone at Kilmacoo is modest in scale, roughly 0.4 metres across and 0.35 metres deep, with a single cavity measuring around 0.23 metres in diameter. What makes its situation particularly curious is a detail offered by the landowner at the time of inspection: several more bullauns were said to exist on the site, yet none could be found. Whether they have been moved, buried under later ground disturbance, or simply lost within the accumulated layers of a working graveyard is not recorded. What remains is one stone, documented and measured, and an account of others that slipped out of reach before anyone thought to look more carefully.