Set against the exterior west wall of a small structure on Scattery Island known as St Senan's Bed, the stone was used as something to sit on, its ancient inscription pressed against the stonework and largely ignored. That inscription, cut along the upper outer edge of a large gritstone slab roughly two metres long and sixty centimetres wide, is now understood to be ogham, one of the earliest forms of writing in Ireland, a script in which letters are represented by a series of notched or scored strokes arranged along a central stem line, typically the edge of a standing stone.

The stone's status as a genuine ogham monument took some time to establish. Writing in 1897, Westropp described it cautiously as bearing 'ogham-like scores', and it was later omitted entirely from Macalister's definitive corpus of Irish ogham inscriptions, compiled in the 1940s. Okasha and Forsyth, writing in 2001, returned to that hesitant earlier assessment. Closer physical examination eventually settled the question. Much of the inscription has been worn away, but towards the left end of the stone, five neatly parallel strokes survive, each six centimetres long and spaced two centimetres apart, forming the ogham letter N. A short gap further to the left yields four more similar strokes, representing either S or part of a second N. The surviving letters are too fragmentary to reconstruct a word or name with any confidence, but their regularity and spacing leave little doubt about what they are. The stone 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 applies digital scanning techniques to record and analyse ogham inscriptions across Ireland.

The stone is now kept inside the refurbished exhibition centre on Scattery Island, which sits in the Shannon Estuary off Kilrush in County Clare. The island is accessible by seasonal ferry from Kilrush Marina, and the exhibition centre provides context for the island's monastic history, of which this battered slab is one of the older and quieter pieces of evidence.