These stones, featuring one or more cup-shaped hollows ground into their surface, are found throughout Ireland and Scotland, though their exact purpose remains a subject of scholarly debate. The depressions, typically circular and ranging from a few centimetres to half a metre in diameter, were likely created through repeated grinding motions over extended periods.

Bullaun stones are generally associated with early Christian sites in Ireland, often found near churches, holy wells, and monastic settlements. The hollows may have served multiple purposes; grinding grain or herbs for medicinal use, holding holy water for blessing rituals, or serving as mortars for preparing pigments. Local folklore frequently attributes healing properties to the rainwater that collects in these basins, with different stones said to cure various ailments from warts to rheumatism.