The mound measures roughly 9.3 metres from north-west to south-east and 12 metres from north-east to south-west, dimensions modest enough that a casual walker might take it for a natural rise in the ground. It is, in fact, the remains of a fulacht fia, one of the most common prehistoric monument types in Ireland, and one of the least understood.

A fulacht fia is essentially a cooking or heating site, typically Bronze Age in date, consisting of a trough dug into the ground, a hearth for heating stones, and the crescentic or kidney-shaped mound that gradually accumulated from the discarded burnt stones after each use. The stones were heated in a fire, then dropped into a water-filled trough to bring it to the boil. Over repeated use, those stones shattered and became useless, and were piled to the side, forming the distinctive curved mound that survives today. What the sites were actually used for remains debated: cooking is the most widely accepted explanation, but proposals have included brewing, textile processing, and bathing. The example at Gortnascregga preserves the characteristic form well, its kidney shape and south-westerly opening consistent with the broader pattern seen across Ireland. What gives this particular site an added point of interest is that a second fulacht fia lies approximately 100 metres to the south-east, suggesting that this corner of north Cork saw repeated or sustained activity during the Bronze Age, though the precise relationship between the two sites is unknown.