Lift it, and the hollow beneath is water-filled. Locally, that water is said to cure warts. The combination of prehistoric carving and continuing folk belief gives this otherwise unassuming boulder a quietly layered quality that is easy to walk past and hard to forget.

Cup-marks are among the most enigmatic features of prehistoric Europe, shallow circular depressions ground or pecked into rock surfaces, whose precise purpose remains genuinely unknown. They appear across Ireland from the Neolithic and Bronze Age periods, sometimes in isolation, sometimes in elaborate groupings. The Tooreen stone, measuring 1.7 metres long and 1.5 metres wide, carries one large cup-mark with a diameter and depth each of around 12 centimetres, alongside three smaller examples. What sets it apart is the fitted stone cover over that principal hollow, a separate piece with a shallow hollow on its own underside, which has been placed there at some point to cap and perhaps protect the water that collects within. Whether the cover is ancient or a later addition is unclear, but the practice of attributing curative power to water gathered in prehistoric rock basins is well documented across Ireland, where such sites often overlap with holy well traditions. Here, the association is specifically with warts, a very particular piece of local knowledge that has plainly persisted alongside the stone for some time.

The stone lies in pasture, so conditions underfoot will vary with the season. The carved hollows are on the upper surface, so they are best examined by approaching closely and looking down rather than across the stone.