It looks, by almost every measure, like a bullaun stone, yet one feature sets it apart from the type: the circular hollow worn into its surface does not simply deepen and stop, as is usual, but continues all the way through, perforating the base entirely. Bullaun stones are boulders, typically associated with early Christian sites, into which one or more cup-shaped depressions have been ground or worn, often believed to have held water used for healing or ritual purposes. This one follows that form precisely, except for the hole that goes clean through.

The boulder itself is sandstone with quartz inclusions, roughly 0.6 metres across and 0.34 metres deep, with a circular depression about 0.3 metres in diameter that narrows as it descends. John O'Donovan, writing in the Ordnance Survey Namebook in 1840, noted that the stone formerly lay beside the gable of a church that once stood adjacent to the site. At some point it was moved, or found its way, to the grounds of the Model Farm house, where it remains today, no longer in its original ecclesiastical context but still carrying that quietly loaded combination of early Christian association and physical anomaly. Whether the perforation is the result of prolonged weathering, deliberate modification, or simply an unusual quirk of the original stone is not recorded.