A bullaun is a large stone, usually boulder-sized, into which one or more cup-shaped hollows have been ground or worn, typically by hand. Their exact purposes remain genuinely uncertain. They appear near early Christian sites often enough to suggest ritual use, perhaps the grinding of pigments or medicines, perhaps the collecting of water thought to have curative properties, perhaps something older still that the Christian period simply absorbed and continued. The water that pools in their hollows has long been associated with healing in folk tradition, and the stones themselves are frequently treated as sacred objects rather than mere tools.

Bullaun stones are found across Ireland in considerable numbers, and Fahburren's example joins a distribution that tells us something about the density of early activity in the west of the country. Mayo is a county with no shortage of prehistoric and early medieval monuments, from megalithic tombs on the slopes of Croagh Patrick to the remarkable field systems preserved beneath the bog at Céide. A bullaun in this landscape fits a pattern without being entirely explained by it, which is rather the point. These stones resist tidy categorisation; they sit at the boundary between the utilitarian and the devotional in a way that keeps archaeologists and folklorists both interested.