In a pasture on the south-eastern side of an early ecclesiastical enclosure at Lackeen in north County Cork, a fulacht fia, one of Ireland's most common yet least understood prehistoric monument types, has been recorded without leaving any visible trace on the surface. A fulacht fia is essentially a burnt mound, the accumulated debris of repeated episodes of fire-cracking stones to heat water, most likely for cooking. They are found in their thousands across Ireland, typically in low-lying or waterlogged ground, and are generally dated to the Bronze Age, though some were in use later. This one, however, is known only through local information, with the material identified around the perimeter of the enclosure rather than in open ground.

What makes the Lackeen site particularly interesting is its relationship with the ecclesiastical enclosure beside it. Early Christian sites in Ireland were often established on or near locations that already carried significance, and the proximity of a fulacht fia to such an enclosure is not unusual in the broader Irish landscape, even if the specific history of how the two features interacted here is unrecorded. The fulacht fia material was noted at the perimeter of the enclosure, suggesting either that prehistoric activity preceded the religious foundation, or that the boundary of the enclosure was later drawn through ground already carrying traces of much older use. Without excavation, it is impossible to say more with confidence.