During topsoil-stripping at the Arcon Mines, Galmoy, between November 1999 and March 2000, archaeologists monitoring the groundworks identified a spread of blackened and fire-shattered stone roughly 14 metres by 16 metres in extent. The material was the unmistakable signature of a fulacht fia, a type of prehistoric cooking or processing site found in considerable numbers across Ireland, typically consisting of a mound of heat-cracked stone accumulated around a water-filled trough into which heated rocks were dropped to boil the contents.

At the centre of the spread, excavators uncovered a sub-rectangular trough measuring approximately 1.5 metres by 1.5 metres and between 0.4 and 0.6 metres deep, orientated roughly northwest to southeast. No lining material had survived, but three stake-holes in the base at the southeastern end suggest that planks or timber boards were once fitted to seal the sides and floor. The trough itself had been deliberately backfilled with the same blackened, fire-shattered stone that made up the surrounding mound, implying a conscious act of closure rather than gradual silting. A compact hearth area, measuring around 1.38 metres by 1 metre, sat at the southeastern end of the trough, where stones would have been heated before being transferred into the water. To the northwest, a large oblong pit measuring 5.3 metres by 2.3 metres was also recorded; its date and purpose remain unknown, and it deepened noticeably from its northwestern end down to 0.7 metres at the southeast, suggesting it was dug with some specific, if now unrecoverable, intention.