A souterrain is a man-made underground stone-lined passage or chamber, typically built in early medieval Ireland for storage or refuge. The fact that inscribed memorial stones were repurposed as building material tells us something about how attitudes toward these monuments shifted over the centuries, their original commemorative function giving way to simple utility.

The stone itself measures 1.88 metres in length and carries an inscription that the scholar R.A.S. Macalister, writing in 1945, described as perfectly legible despite the rather rough surface of the stone. He read it as BROINIENAS KOI NETA TTRENALUGOS, a formula typical of early ogham commemorations. Ogham is a script used primarily in Ireland and parts of Britain between roughly the fourth and seventh centuries, in which letters are represented by notches and strokes cut along the edge of a stone. A later reading by Damian McManus in 1991 agreed with most of Macalister's transcription but found the final three characters, U, O, and S, more difficult to confirm. The stone was first reported during a discovery at the souterrain in 1896, and was subsequently purchased by the Royal Irish Academy before passing into the collection of the National Museum of Ireland, where it remains. More recently, the stone has been documented as part of the Ogham in 3D project run by the School of Celtic Studies at the Dublin Institute for Advanced Studies, which produces high-resolution digital scans of ogham stones across Ireland and Britain.