It served as a lintel for an outbuilding, its carved surface presumably visible to anyone who cared to look, its meaning long since detached from living memory. Now it rests on the grass-grown rubble of that same collapsed structure, which has since fallen around it.

Ogham is an early medieval script used primarily in Ireland between roughly the fourth and seventh centuries, in which letters are represented by groups of notches and strokes cut along the edge or face of a stone. The Glanmore stone, measuring 1.26 metres in length and just 13 centimetres thick, carries a single name along one of its long angles: GANICCA. The inscription is clearly legible, with one minor anomaly. The final vowel notch, the closing A, is cut differently from the others and does not extend across the edge of the stone in the usual manner. Whether this reflects a slip of the carver's hand, a deliberate variation, or something else entirely is not recorded. R.A.S. Macalister, the scholar who catalogued hundreds of ogham stones across Ireland in the mid-twentieth century, noted the stone's situation as early as 1945, by which point its original provenance was already unknown. Where it stood before someone repurposed it as building material, and who GANICCA was, remain open questions.