A seventh ogham stone had been pressed into service as a prop, holding up a larger stone that had cracked sometime in antiquity. When workmen building a field boundary across a slight rise in the Dunloe Castle demesne stumbled upon the souterrain, a roofed underground stone-lined passage typically used in early medieval Ireland for storage or refuge, in 1838, they also found bones and skulls inside it, some believed to be human. The original builders of the souterrain had, at some point, repurposed a collection of commemorative inscribed stones as raw building material, sealing them underground where they remained, undisturbed, for centuries.

The stone now standing near the public roadway at Coolmagort is 2.65 metres tall and up to 46 centimetres wide. Its inscription runs along both edges and reads, in ogham: MAQI-RITEAS MAQI MAQI-DDUMILEAS MUCOI TOICACI, a genealogical formula naming an individual, their father, and their kin group, the kind of memorial text common to early Christian Ireland. The stone had fractured near its centre while still inside the souterrain and was held in place by an upright stone beneath it. A small rectangular area on one edge was identified by the scholar R. A. S. Macalister, writing in 1945, as a deliberate obliteration of a mistakenly carved character, a kind of ancient correction. In 1940 the Office of Public Works removed all seven ogham stones from the souterrain and re-erected them close to the road. The souterrain itself was then filled in, and no surface trace of it remains. The stones, displaced twice over, now stand in open air, their inscriptions preserved well enough to be captured in high-resolution three-dimensional scans as part of ongoing research into the ogham corpus.