This kind of stone is known as a bullaun, from the Irish word for a rounded hollow or bowl, and examples like this one are found scattered across early Christian sites throughout Ireland. Their original purpose remains genuinely uncertain; theories range from grinding or pounding vessels to receptacles for water used in blessing or ritual. What gives this particular one an additional layer of interest is that it is not alone.

The stone itself measures approximately 0.55 by 0.6 metres, and the hollow at its centre widens from a diameter of around 0.1 metres at the base to 0.35 metres at the top, with a depth of roughly 0.11 metres. It sits within a broader early ecclesiastical enclosure, the kind of bounded sacred space that formed the nucleus of early Christian monastic or church settlements across Ireland, often preserving in their outlines centuries of continuous religious use. The burial ground it belongs to occupies part of that same enclosure, and the bank on which the bullaun rests runs east to west in a linear form. A second bullaun stone has also been recorded at the same site, making Kilmaculla one of those relatively uncommon places where a pair of these objects survive together within a single ecclesiastical landscape.