Cut into its upper surface is a single wide depression, circular in shape and about fifteen centimetres deep. At its base, a modern inscribed slab spells out in capital letters: HOLY WATER FONT CURE FOR HEADACHES. It is a quietly strange combination, the ancient hollow worn into the rock and the matter-of-fact modern caption, both pointing to the same unbroken belief in the water's efficacy.

A bullaun stone is a large rock, usually glacial or naturally occurring, into which one or more cup-shaped hollows have been ground, most often associated with early Christian monastic sites in Ireland. The water that collects in these depressions was widely considered to have curative or protective properties. This particular stone lies about twenty-five metres east of Kilkieran graveyard, perched on the stone revetment that partially encloses the adjacent holy well, and it is closely associated with the early medieval monastery of Kilkieran and its church. Writing in 1905, the historian William Carrigan described the stone simply as a holy water font, a designation the modern inscription has preserved in its own blunt way. Two further bullaun stones were found within the graveyard itself, uncovered during a clean-up operation in 1985, suggesting this small hilltop complex was once considerably more active as a site of devotion than its quiet present appearance might suggest.

The setting adds something to the object. The slope faces south across the valley of the River Suir, and the well and its sandstone companion sit in that open, slightly exposed position that many early monastic sites in Ireland seem to favour, visible to the valley below and oriented toward the light. The stone is free-standing rather than embedded in a wall or structure, which makes it easier to examine the depression closely, a rough circle measuring roughly thirty centimetres across, wide enough to cup both hands.