This is a fulacht fia, a type of prehistoric cooking site found in extraordinary numbers across Ireland, particularly in low-lying, waterlogged ground close to streams. The site takes the form of a partially eroded mound, roughly nine metres north to south and six metres east to west, rising just over a metre above the surrounding terrain. Its curved opening, about three metres wide, faces eastward towards a nearby stream, an arrangement entirely typical of the form.

A fulacht fia generally operated by heating stones in a fire until they were intensely hot, then dropping them into a water-filled trough to bring the water rapidly to the boil. The shattered, heat-crazed stones that resulted from repeated thermal shock were raked out and piled to either side of the trough, gradually building up the distinctive horseshoe-shaped mound that archaeologists recognise today. The charcoal-enriched soil within the mound at Derryclogher is a direct remnant of those repeated firings. Traces of burnt material visible one to three metres east of the mound are thought to be eroded portions of it, spread gradually downslope or shifted by water over time. The proximity of the stream to the east would have been essential to the whole process, providing a reliable water source.

The site does not stand in isolation. An enclosure lies roughly ninety metres to the north-east, and relict field boundaries survive about a hundred metres to the west, the ghosted outlines of a farming landscape that once surrounded this place. Whether those features were contemporary with the fulacht fia or represent later activity in the same ground is not certain, but together they suggest that this boggy corner of Cork was, at various points, a worked and inhabited stretch of land rather than a marginal backwater.