It measures roughly 18 metres north to south and just under 14 metres east to west, rising on average less than half a metre above the surrounding soil. What gives it away, to those who know what to look for, is the colour: patches of dark, almost charcoal-black earth visible through the grass, quite distinct from the brown soil around it, along with the fractured stone that makes up its bulk. This is a fulacht fiadh, a type of prehistoric cooking or industrial site found in considerable numbers across Ireland, typically identified by the distinctive crescent or horseshoe-shaped mound of fire-cracked stone that accumulates beside a water trough. The usual method involved heating stones in a fire, then dropping them into a water-filled pit to bring it to the boil. At Flemby, no trough is visible at the surface, though the depression beneath the mound hints at where one may once have been.

A partial excavation carried out in 2000 and work connected to the N22 road improvement scheme brought the site into sharper focus. Testing of the surrounding field uncovered burnt spreads of soil and shattered stone, along with the remains of at least one further fulacht fiadh. A radiocarbon date returned from one of those spreads placed activity here at between 4210 and 4190 BC, pushing occupation of the site back into the Mesolithic or very early Neolithic period, an unusually early date for this type of monument, which is more commonly associated with the Bronze Age. Aerial photography of the same field revealed traces of up to three other similar features, though none of these retain any above-ground presence today. The concentration of sites, and the patches of dark soil still showing through the grass, suggest that this one field may once have been a repeatedly used, purposeful location beside the small unnamed stream that runs approximately 35 metres to the east. The research context for the site comes from Michael Connolly's 2008 doctoral thesis on the prehistoric settlement of the Lee Valley, Tralee, which examined the area as a broader landscape rather than a collection of isolated monuments.