That pairing, a bullaun and its rubber stone still together after what may be many centuries, is quietly remarkable. Bullaun stones are boulders with one or more deliberately carved or worn basins, found at early Christian and earlier sites across Ireland. They were used for grinding, possibly for preparing pigments, medicines, or grain, and in later folk tradition the water that collects in their basins was believed to have curative properties. To find one with its grinding stone still in place, fitting the basin as though it never left, is unusual.

The stone at Ballynilard is oval in shape, roughly 0.75 metres by 0.65 metres, with a deep central basin about 0.37 metres across and 0.25 metres deep. The rubber stone, also oval, measures around 0.2 metres in diameter and sits neatly within it. The wider setting adds to the interest. The bullaun lies at the base of the western face of a high cross, with a church some 20 metres to the north and a holy well approximately 257 metres to the north-west. This clustering of monument types, cross, bullaun, church, and well, is characteristic of early medieval ecclesiastical sites in Ireland, where different forms of devotional and practical life occupied a shared, bounded landscape. The site sits on a low rise with open views in every direction, which would have made it a legible and probably significant point in the local terrain.