What it actually represents is one of the more curious recurring features of the Irish prehistoric landscape: a fulacht fia, or burnt mound, the remnant of an ancient cooking site where stones were repeatedly heated in fire and dropped into a water-filled trough to bring it to the boil. The process left behind a characteristic horseshoe or oval heap of fire-cracked, heat-shattered stone, and these mounds are found in their thousands across Ireland, almost always close to water or boggy ground.

This particular example measures roughly 15.6 metres long, 20.4 metres wide, and still stands to a height of about 1.5 metres, which suggests a reasonable degree of preservation beneath the vegetation. Its opening, some 16.2 metres across, faces south-east. Most fulachtaí fia date to the Bronze Age, broadly between 1500 and 500 BC, though some have produced earlier or later dates. The marshy setting here is entirely typical; proximity to a reliable water source was essential to the whole operation. What makes the Carhoo site a little more interesting than it might otherwise seem is that a second fulacht fia lies approximately 150 metres to the north-west, suggesting this corner of mid Cork saw repeated or sustained activity of this kind rather than a single isolated episode.