The discovery was a fulacht fia, one of the most common prehistoric monuments in Ireland, and yet one that still generates genuine debate about its purpose. The basic form is consistent across thousands of sites: a mound of fire-cracked stones beside a trough, usually in a wet or marshy location. The working theory is that stones were heated in a fire, dropped into a water-filled trough to bring it rapidly to the boil, and used for cooking, though brewing, hide-working, and bathing have all been proposed. This particular example, disturbed already by modern land drainage, survived as a shallow irregular spread measuring roughly 7.2 metres north to south and 5.3 metres east to west, at a depth of only one to two centimetres.

Excavation uncovered three pits cut into the subsoil beneath the spread. The most clearly defined was a rectangular pit at the northern end, interpreted as a trough, the vessel into which heated stones would have been dropped. Two further pits to the west contained mixtures of both burnt and unburnt stone, and were read either as additional troughs or as storage pits associated with the site's use. What makes the find particularly interesting is that it did not stand alone. A second fulacht fia was identified and excavated approximately 16 metres to the south-east, suggesting that this low-lying marshy corner of Corkbeg was visited and used repeatedly, perhaps across generations, by people who found the wet ground and ready water supply well suited to whatever process they were carrying out. The proximity of two sites to one another is not unique in the Irish record, but it gives a small added texture to what might otherwise read as a routine salvage excavation conducted under the pressure of an imminent construction deadline.