The stone, roughly 0.4 by 0.5 metres, may once have formed part of the roof of a souterrain, a type of dry-built underground passage or chamber associated with early medieval settlement in Ireland, typically used for storage, refuge, or both.

The structure came to light in 1983 when ploughing broke through into it, prompting an official record. When the site was inspected four years later, in 1987, a short section of the passage was still accessible and measured just 0.45 metres in width, narrow enough to squeeze through rather than walk. Built without mortar using carefully laid stones, it ran on an east-west axis along the brow of a north-south ridge. By the time it was recorded, it was already largely infilled, and little further excavation appears to have followed. About 200 metres to the south-east lies a ringfort, the circular earthwork enclosures that were the typical farmstead units of early medieval Ireland, and the proximity of the two features is unlikely to be coincidental. Souterrains are frequently found in association with ringforts, often positioned just outside the enclosing bank and connected to the domestic life of whoever lived within.