It measures just 0.68 metres in length and 0.35 metres across, and on one face someone has incised a Greek cross, the kind with four arms of equal length, enclosed within a circle. The combination of cross and circle is one of the earliest and most enduring forms of Christian marking in Ireland, used to claim ground, commemorate the dead, or simply declare the presence of a sacred space. This particular stone does all of that quietly, in a compact geometry that has barely aged.

The slab was found around 1930 at Cill Lachtaín, an early ecclesiastical site outside Cork city. Cill is the Irish word for a church or monastic enclosure, and sites bearing the name often preserve traces of very early Christian settlement, sometimes pre-dating the more familiar round-towered monasteries of the ninth and tenth centuries. The stone was donated to the UCC Museum and noted in print by Power in 1931, before eventually passing into the collection of Cork Public Museum. Its origin at Cill Lachtaín is what gives it weight; without that provenance, it would be a modest carved stone. With it, the incised lines become a material remnant of a community that once gathered at that spot, now largely disappeared from the landscape above ground.