It is a bullaun stone, a type of ancient stone, usually granite or another hard rock, that carries one or more rounded depressions ground into its upper surface. The function of these hollows is not definitively settled; they may have served as mortars for grinding, as vessels for water used in ritual or healing, or both at different points across a very long life. This particular example is a roughly circular conglomerate boulder, measuring about 82 centimetres across and 36 centimetres high, with a single circular depression roughly 15 centimetres deep worn into its top face.

The stone did not originate at its present address. It was moved here from St Kieran's church at Modreeny, a site with its own layered early medieval history. The relocation to the forecourt of St Michael and John's Roman Catholic church, to the south-east of Cloughjordan village, is a pattern seen elsewhere in Ireland, where bullaun stones associated with early ecclesiastical sites were gathered up and repositioned, sometimes out of reverence, sometimes simply out of a desire to preserve something clearly ancient. The plinth on which it now rests is itself a reused limestone block, which adds a quiet additional layer to the object's accumulated biography. One old stone supporting another, neither quite in its original context.