Kidney-shaped and roughly a metre high, measuring about thirteen and a half metres long and thirteen metres wide, it sits at the base of an east-facing slope beside a stream, overgrown and easy to mistake for a natural feature of the landscape. It is, in fact, the remains of a fulacht fia, one of the most common yet least understood monument types in the Irish countryside.

Fulachtaí fia (the plural form) are prehistoric cooking sites, found in their thousands across Ireland and dating mostly to the Bronze Age, roughly 2000 to 500 BC. The basic method involved heating stones in a fire and dropping them into a water-filled trough to bring it to a boil. The cracked and shattered stones were then discarded into a pile nearby, and it is this accumulated debris, dark with charcoal and fire-reddened fragments, that forms the characteristic mound visible today. The kidney or horseshoe shape is typical of the type, caused by material building up on either side of the central trough over repeated use. Why they were used is a matter of ongoing discussion among archaeologists; cooking meat is the traditional explanation, but brewing, hide-working, and bathing have all been proposed as alternative or additional functions. The siting of the Curraghdermot example beside a stream is entirely characteristic, since a reliable water source was essential to the whole operation.