Ogham is an early medieval script, typically carved as a series of notches and strokes along the edge of a stone, and was used in Ireland roughly between the fourth and seventh centuries to record personal names, often in memorial contexts. This particular stone, 1.2 metres tall and relatively slender, carries the inscription CUNACENA, most likely a personal name. Rather than standing upright in open ground as such stones are usually found today, it was pressed into service as a structural prop inside a souterrain, an underground passage or chamber of the kind built in early medieval Ireland, often for storage or refuge.

The souterrain in question lay beneath a slight rise in the Dunloe Castle demesne in Coolmagort and was discovered in 1838 by workmen digging a field boundary. What they found was a roofed underground passage covered by nine stone slabs, six of which bore ogham inscriptions. A seventh stone, this one, stood upright in the passage supporting a cracked lintel above it. Along with the stones, a number of bones and skulls were found inside, some of them reportedly human. The structure had been marked simply as "Cave" on Ordnance Survey maps, giving no hint of what lay beneath. In 1940, the Office of Public Works removed all seven ogham stones from the souterrain and re-erected them beside a nearby public road. The souterrain itself was filled back in, and no trace of it now remains at the surface. The stone carrying CUNACENA has since been examined as part of the Ogham in 3D project run by the School of Celtic Studies at the Dublin Institute for Advanced Studies, which has produced detailed digital records of inscribed stones across Ireland.