It was intended to become a bullaun stone, a type of ancient worked rock bearing one or more hollowed basins, which are found across Ireland and are generally associated with early Christian or pre-Christian ritual use. What makes this particular example quietly arresting is that the work stopped before the basin was complete, and the evidence of that interrupted labour is still visible on the surface.

The stone is D-shaped in plan, with two straight edges measuring roughly 42cm and 23cm, and a height that varies between 14cm and 22cm, the unevenness caused by an accidental chip taken from the underside. Its single basin, around 19cm by 20cm across and only 4cm deep at most, was being pecked out by hand when work ceased. The peck marks left by that process are still clearly legible on the stone; had it ever been finished and put to use, repeated grinding would have smoothed those marks away entirely. What survives is essentially a record of craft caught mid-process. The site itself carries its own layer of historical strangeness. The slope originally overlooked the valley of the River Liffey, but that landscape was deliberately submerged when the Pollaphuca reservoir was created. The stone, and other archaeological features nearby, only became visible again when water levels in the reservoir dropped low enough to expose the ground beneath.