That year, the ground gave way and revealed a souterrain, an underground stone structure of the kind commonly associated with early medieval ringforts, typically used for storage, refuge, or both. What makes this one quietly notable is how much of it remains unexamined: one of its two chambers was found filled with soil and simply left that way.

The structure sits within a ringfort, a circular enclosed settlement of the early medieval period, and was investigated by M. J. O'Kelly of University College Cork following its accidental discovery. According to McCarthy's 1977 account, the souterrain comprised at least two corbelled chambers, meaning the walls were built with stones laid in overlapping courses to form a self-supporting roof, a technique that requires no mortar and considerable skill. The first chamber ran roughly north to south, measuring about 3.75 metres long, 1.5 metres wide at its widest point, and just 1.25 metres high, with a slight widening towards the centre. Its floor was covered with stones and collapsed roof material, beneath which lay a layer of dark soil some 20 to 40 centimetres deep. At the northern end, a narrow creepway framed by a lintel and stone jambs connected to the second chamber. That second chamber, also oriented north to south, was found completely filled with soil and was never excavated. Charcoal and animal bones recovered from the northern end of the first chamber hint at some kind of activity there, though the record does not say more.

Today the site leaves no visible trace on the surface, which is often the case with souterrains once their roofs have been disturbed or repaired. The unexcavated second chamber means that whatever else the structure once held, including any further finds or clues about its date and use, remains unrecorded.