That opening is the probable entrance to a souterrain, an underground stone-lined passage or chamber constructed during the early medieval period, most commonly as a place of storage, refuge, or concealment. The combination of the enclosure, the unusual mound form, and the subterranean element makes this a quietly layered site, several phases of human use folded into a single field corner.

The enclosure itself is a circular univallate rath, meaning a roughly circular farmstead defended by a single earthen bank. The bank here is well-defined and around six metres wide, and the interior ground level sits noticeably higher than the surrounding land, a common result of centuries of occupation accumulation. In the south-western sector, the kidney-shaped mound curves back towards that bank, with the souterrain opening positioned at the top of its inward curve, measuring approximately 2.4 metres by 2.2 metres. To the north of this main mound lie two further earthworks: a smaller mound roughly 2.6 metres by 2 metres, and, about four metres to the east, a sub-circular mound measuring around 4 metres by 3.4 metres. The relationship between these secondary features and the souterrain is not spelled out, but their proximity within the same enclosure suggests the site accumulated structures over time rather than being built to a single plan. The archaeological detail comes from C. Toal's North Kerry Archaeological Survey, published in 1995.