The fit is close enough to suggest intention rather than accident, and that pairing of container and contained is what marks this out as a bullaun stone, a category of ancient carved or worn rock found across Ireland, typically associated with early Christian or prehistoric ritual use. The word bullaun comes from the Irish for bowl, and these basin-like hollows, cut or ground into boulders, were used for purposes that remain only partly understood, ranging from grinding and processing to votive practice.

This particular example is a granite boulder roughly 1.7 metres long, 0.9 metres wide, and 0.75 metres deep, with a flat upper surface. Into that surface has been worked a depression measuring 0.75 metres by 0.4 metres and about 0.33 metres deep, and within that hollow sits a close-fitting stone of its own, at 0.65 metres by 0.35 metres by 0.28 metres. It came to light not through excavation but during reclamation work on a low rounded rise in the townland of Labanasigh, and the rise itself is reputed to carry that name in the local tradition. The presence of a named, reputedly significant landform adds a layer of interest to an already unusual find; the reclamation work that disturbed the site also preserved its memory by bringing the stone to attention.