That uncertainty is not a gap in the record so much as the point of the place. A souterrain, for those unfamiliar with the term, is a dry-stone or rock-cut underground chamber or passage, usually associated with early medieval settlement in Ireland, and thought to have served as storage, refuge, or both. The one at Cappyaughna exists, at present, more as a question than a confirmed feature.

The entrance was first noted in 1993, when a local contact, Connie Murphy, observed it on an eroded earthen mound that had been disturbed by badger burrowing. Badgers are, inadvertently, among the more productive excavators of buried archaeology in Ireland, and their activity here was what first exposed whatever opening was visible. By 2004, however, the site had become so densely colonised by rhododendron that investigators could not locate it at all. Rhododendron ponticum, an introduced species that has spread aggressively across the wet Atlantic woodlands of southwest Ireland, is notoriously difficult to clear, and its dense canopy and root systems can effectively bury a landscape in plain sight. The mound and its possible passage vanished back into the undergrowth. Two enclosures lie nearby, roughly forty and sixty metres away to the north and east respectively, which suggests the area once held some form of organised early settlement, even if the souterrain itself remains elusive.