The hollow measures roughly 0.9 metres across and drops only about 45 centimetres, modest dimensions that would barely attract a second glance. Yet its position, sitting around ten metres inside the ringfort's bank, suggests it may mark the roof of a collapsed souterrain.

Souterrains are underground stone-lined passages or chambers, typically constructed during the early medieval period and associated with ringforts across Ireland. They were likely used for cold storage, refuge, or both, and their entrances were often deliberately concealed within the enclosure of the fort they served. When the corbelled or lintelled roofing of such a passage gives way over the centuries, the result is precisely the kind of subtle surface depression visible here. The ringfort at Dooneens, recorded separately, provides the wider context for this feature, and the two together represent a fairly typical, if understated, example of early medieval rural settlement in mid Cork.