It measures roughly five metres by four, rises less than a metre from the ground, and is composed almost entirely of burnt material. This is a fulacht fia, a type of prehistoric cooking or processing site found in enormous numbers across Ireland, typically dating to the Bronze Age. The usual interpretation is that stones were heated in a fire, dropped into a water-filled trough to bring it to the boil, and used to cook meat or to process other materials; the discarded, shattered, fire-cracked stones accumulated over time into exactly these kinds of low, scorched mounds. Thousands survive across the country, often beside streams or marshy ground, and this example on the east bank of the Coomeelan is a typical representative of the type.

What makes the Gearhanagoul site more than just an isolated cooking mound is the company it keeps. Within thirty to forty metres of the fulacht fia lie at least three enclosures and a possible boulder-burial, the latter a form of prehistoric interment in which a large stone is placed over or beside human remains. The clustering of these features suggests that this quiet valley slope saw sustained use over a considerable period, with different activities and perhaps different kinds of significance layered onto the same landscape. The indentation along the western side of the mound and the exposed burnt material at its southern end give the site a slightly raw, unfinished quality, as though it has been gently eroding back towards the stream that once made it useful.