But the small patch of disturbed soil at the edge of one mound tells a different story: heat-fractured stones and traces of charcoal, the unmistakable signatures of a fulacht fia, one of Ireland's most common yet persistently mysterious prehistoric monument types. A fulacht fia is essentially a cooking place, the standard interpretation being that stones were heated in fire and dropped into a water-filled trough to bring it to the boil, leaving behind the characteristic crescentic mound of cracked, fire-blackened stone that accumulates over repeated use. They are found in their thousands across Ireland, typically close to water, and this example is no exception, positioned on the southern bank of a small stream.

The site actually comprises two mounds rather than one. The north-western mound is the smaller of the pair, measuring roughly three metres by two metres and rising to about 0.8 metres on its north-eastern side. The south-eastern mound is larger, approximately 5.5 metres by 4.1 metres and up to 1.1 metres in height, though it loses definition where it merges with a natural rise in the ground to the west and south-west, and exposed rock outcrops blur its edges. Between the two mounds lies an irregularly shaped hollow that opens northward toward the stream, flanked on its southern side by a low face of natural rock. This configuration does not produce the classic crescent or horseshoe plan often associated with fulachta fiadh, but the presence of burnt and heat-shattered stone in both mounds, along with charcoal traces, points clearly enough to the same tradition of repeated high-temperature activity. The site lies 150 metres south-west of Doonallia Fort, though neither monument is visible from the other, each occupying its own fold in the coastal landscape.