This is a fulacht fia, a type of prehistoric cooking site found in enormous numbers across Ireland, typically consisting of a trough dug into the ground, a nearby hearth for heating stones, and the accumulated mound of discarded burnt material that results from repeatedly plunging hot rocks into water to bring it to the boil. At Knockagolig, a forestry trench cut into the north-east side of the mound has inadvertently provided a cross-section of the interior, revealing a layer of burnt material up to twenty centimetres deep. Towards the north-north-west end, the composition shifts, becoming less stony and more charcoal-rich, which may indicate where the hearth itself once stood.

The mound measures roughly 12.7 metres along its longer axis and 7.5 metres across, and it does not stand alone. It forms part of a cluster of four such sites in the immediate area, a grouping that suggests repeated or sustained use of this particular stretch of ground over time. The broader significance of this cluster was noted at least as far back as 1934, when Bowman recorded what may be the same four monuments in an archaeological journal. O'Shaughnessy revisited and described the site in 1997, and it was subsequently included in the published inventory of north Cork's archaeological heritage. The concentration of fulachta fiadh here is not unusual in a national sense, as these sites often occur in loose groups near water sources, but it gives Knockagolig a particular density of prehistoric presence that rewards attention.