It is a thin dark smear in the earth, a layer of burnt and heat-shattered material no more than twenty centimetres deep, exposed only because forestry workers cut drainage trenches through the ground and happened to slice across something far older.

A fulacht fia (also spelled fulacht fiadh) is a type of prehistoric cooking site found in great numbers across Ireland, typically consisting of a trough, a hearth, and a mound of fire-cracked stones left over from repeatedly heating water by dropping stones into it. They are generally dated to the Bronze Age, though the tradition may have persisted across a wide span of time. At Knockagolig, the burnt layer runs five to six metres in length and appears in two parallel forestry trenches roughly ten and a half metres apart, though the layer is not in perfect alignment between them, with the exposure in the more easterly trench sitting some two to three metres to the south-east of its counterpart in the western one. Whether this slight offset reflects the natural spread of a single site, later disturbance, or simply the uneven survival of material is difficult to say. O'Shaughnessy, writing in 1997, considered it probably the remains of a single fulacht fiadh. The site may also be one of four such monuments in the area recorded by Bowman in 1934, suggesting this part of north Cork was once a place of repeated prehistoric activity, though the connection remains tentative.