A bullaun is a boulder or slab bearing one or more artificial cup-shaped hollows, ground into the rock surface in prehistory or the early medieval period; they are found across Ireland, often near ecclesiastical sites, and were frequently associated with ritual, healing, or cursing traditions in local folk practice. The fact that this one has been incorporated into the fabric of the wall itself sets it apart, suggesting it was deliberately retained when the wall was constructed or repaired, rather than discarded or moved aside.