It is easy to walk past without a second glance, yet the shallow circular hollow worn into its upper surface marks it out as something considerably older than the church it now accompanies. This is a bullaun stone, a type of boulder, usually of considerable age, distinguished by one or more cup-shaped depressions ground or worn into its surface. Bullauns are found across Ireland, often in association with early medieval ecclesiastical sites, and the water that collects in their basins was traditionally held to have curative or ritual significance.

This particular stone is not native to the church grounds. It was originally associated with St Keran's church at Modreeny, an early ecclesiastical site whose patron, St Ciarán of Saighir, is among the older figures in Irish hagiography. At some point the stone was relocated to its present position, where it now rests on a plinth assembled from late limestone blocks, fixed in place with cement. The boulder itself is conglomerate, a sedimentary rock composed of rounded fragments bound together, which gives it a visibly coarser texture than the limestone surrounding it. The central depression measures roughly 0.15 metres deep and about 0.4 by 0.36 metres across, set into a boulder standing 0.36 metres high and nearly a metre in its longest dimension. It is a modest object by any measure, but the displacement from its original site and its subsequent cementing into place captures something of the ambivalence with which such pre-Christian or early Christian objects have been treated over the centuries, preserved but also, in a sense, pinned down.