He did not know it at the time, but those reddened, heat-fractured stones were almost certainly the last material evidence of a fulacht fia, a type of prehistoric cooking site found in considerable numbers across the Irish landscape. A fulacht fia typically consists of a horseshoe-shaped mound of fire-cracked stone accumulated beside a trough or water source, where stones were heated in a fire and then dropped into water to bring it to a boil. The trackway construction at Capnagower appears to have effectively erased the site.

What survives is fragmentary but legible. The fulacht fia sits at the lower, south-eastern end of a peat basin behind the O'Malley house, close to the outflow point of a stream, and it is not alone in the landscape: two further fulachtaí fia overlook the same basin from its north-western end. A mass of heat-fractured stone roughly eight metres long is still visible in the face of the embankment on the south-western side of the trackway. On the north-western side, approximately 30.6 metres from the house, a small grassy mound, roughly 3.4 metres by 2.5 metres and only about 0.4 metres high, has been partially dug into, exposing another concentration of burnt stone, with a large boulder protruding from its south-western face. Just under three metres to the north of this mound, a curving earth and stone bank stretches 15.3 metres in length, standing up to 0.75 metres high. Whether this arc represents the remains of yet another fulacht fia, or is simply the residue of more recent landscaping associated with the house or the trackway, remains genuinely uncertain.