The site is tentatively identified as a souterrain, an underground stone-lined tunnel or chamber typically built during the early medieval period in Ireland, often used for storage or as a place of refuge. What makes this particular example unusual is how little of it remains visible or accessible; only that one stone, which may be the remnant of a blocked-up entrance, hints at what might lie beneath.

The souterrain sits within, or just inside, an associated ringfort, a type of circular enclosure defined by earthen banks or stone walls that served as a farmstead during the early medieval centuries. The two features together suggest a settlement of some complexity, where the underground passage would have complemented the defensive and domestic functions of the enclosure above ground. The detail comes from a 1994 archaeological survey of the Ballinrobe district compiled by D. Lavelle, which placed this feature among hundreds of recorded monuments around Lough Mask and Lough Carra. At the time the survey was carried out, the souterrain was recorded as inaccessible, and the identification itself was offered with some caution, the large stone being the only physical evidence visible on the surface.