What looks at first glance like an unremarkable rise in the ground is in fact the accumulated debris of a fulacht fia, a type of ancient cooking site found in great numbers across Ireland, particularly in low-lying, wet ground near water sources. The characteristic material is fire-cracked stone, shattered by repeated heating and quenching, which builds up over time into the rounded mounds that still dot the Irish countryside in their thousands.

The Clodah site sits in marshy ground close to a stream, a setting entirely typical of this kind of monument. Fulachtaí fia, as they are known in the plural, were generally in use during the Bronze Age, roughly between 1500 and 500 BC, though some examples have been dated earlier. The basic method involved heating stones in a fire and dropping them into a water-filled trough to bring the water to boiling point, a technique suited to both cooking and, as some researchers have proposed, a range of other activities including textile processing or bathing. At Clodah, the burnt and shattered stone that forms the mound is not only visible as a grass-covered spread on the surface but has also been exposed in the cut face of a drainage ditch running parallel to the stream, where the dark, heat-fractured material shows clearly in section. That kind of accidental exposure, where field drainage cuts through a buried deposit, is one of the most common ways these sites come to notice at all.