This is a fulacht fia, a type of ancient cooking or processing site found in large numbers across Ireland, typically consisting of a mound of fire-cracked stones accumulated beside a water source. The characteristic method involved heating stones in a fire and dropping them into a water-filled trough to bring it to boiling point, leaving behind the shattered, heat-damaged stone that forms the mound. At Coornacaragh, that mound measures roughly 7.6 metres on its north-east to south-west axis and 6.7 metres across, standing about 0.8 metres high, with its opening facing south-west.

What makes this particular site quietly interesting is not just the mound itself but the concentration of related features immediately around it. A second possible fulacht fia lies just to the north-east, and a spread of burnt material sits to the north-west on the opposite bank of a nearby stream, suggesting this stretch of hillside saw repeated or prolonged use. The three features together point to deliberate, perhaps habitual, activity at this location, with the stream providing the water supply that such sites require. The eastern half of the mound at Coornacaragh was disturbed during drainage works at some point, which is a common fate for low earthworks in improved farmland, but enough survives to read the original form clearly.