It is not dramatic to look at, barely a metre and a half above the surrounding soil, but what it represents is one of the most common and still somewhat mysterious monument types in the Irish landscape. A fulacht fia is a prehistoric cooking site, typically identified by a horseshoe or oval mound of burnt and shattered stone. The standard interpretation is that stones were heated in a fire, dropped into a water-filled trough, and used to bring the water to boiling point, probably for cooking meat. The proximity of this particular example to natural springs is entirely characteristic; these sites are almost always found near reliable water sources.

The mound at Nettleville measures 34.5 metres in length and 22.5 metres in width, which places it towards the larger end of the scale for this monument type. Most fulachtaí fia date to the Bronze Age, broadly speaking the period from around 2500 to 500 BC, though some have produced later dates. The accumulated mound material consists of the discarded burnt stone, cracked and blackened through repeated heating and sudden cooling, which builds up over what may have been many episodes of use across generations. A small section of the Nettleville mound has been ploughed over, a common fate for low earthworks in cultivated land, but the bulk of the monument appears to survive.