The Ballynahina fulacht fia, a term used for these distinctive burnt mounds, represents a technology both simple and labour-intensive: stones were heated in fire, dropped into a water-filled trough to bring it to the boil, and used to cook meat or, as some researchers have argued, for bathing or industrial processes. The mound itself is the accumulated debris of that repeated heating and cracking, a low ridge of fire-shattered stone and blackened soil that can persist in the ground for thousands of years.

The site came to light in 2003 during archaeological work carried out ahead of the construction of the N8 Rathcormac-Fermoy Bypass in County Cork. Excavation revealed a mound measuring twelve metres east to west and eight metres north to south, composed of heat-shattered stones and charcoal-enriched soil, the characteristic signature of a fulacht fia. Alongside the mound, investigators recorded forty-three associated features, among them two definite troughs, a possible third, and a number of shallow pits. Troughs, often timber-lined or cut into the subsoil, are the functional core of these sites; without a trough to hold water, the whole heating process has no purpose. The concentration of features at Ballynahina suggests a site that saw sustained, repeated use rather than a single episode of activity.