A fulacht fia is essentially a burnt mound, the accumulated debris of a Bronze Age cooking or heating site where stones were repeatedly fired and plunged into a water-filled trough to raise the temperature. Thousands survive across the Irish landscape, typically as low, horseshoe-shaped mounds of heat-shattered stone and dark, charcoal-rich soil sitting close to a water source. The example at Carrigboy, though, survives only partially, its original mound having been levelled during drainage works at some point in the past.

What remains is visible as a section of burnt material exposed along the stream bank, a cross-cut slice through the archaeology that local information confirms was once a more substantial mound before the land was drained and cleared. This kind of inadvertent exposure is, in a grim way, useful: the dark scorched layer and fragmented fire-cracked stone in the bank section offer a readable record of what the site once was, even as the mound itself is gone. The association with the stream is typical. Fulachtaí fia almost invariably sit beside running water, which was both practical and perhaps meaningful to the people who used them during the Bronze Age, roughly 4,000 to 2,500 years ago.