A fulacht fia, broadly speaking, is a Bronze Age cooking or heating site: stones would be heated in a fire and then dropped into a water-filled trough until the water boiled, a method that leaves behind exactly the kind of debris found here, a spreading mound of heat-shattered stone, charcoal, and ash. What makes sites like this quietly compelling is how ordinary they once were, and how thoroughly they vanished.

Excavated under licence in 2006 by Zajac, the Farrannoo site had been levelled at some point in the past and lay beneath a shallow layer of peat, leaving no surface trace before the soil was stripped back. Beneath the mound, which measured roughly 5.8 metres north to south and 5.2 metres east to west, was an unlined circular trough approximately 1.3 metres in diameter and 0.6 metres deep, with a flat base and steep sides. The lowest fill of the trough contained burnt stone and angular boulders, with compacted peat above. Two post holes were also identified, one close to the trough and one roughly six metres to the east, hinting at some kind of timber structure associated with the site, though its form remains unclear. No artefacts turned up in direct association with the fulacht fia itself, though three pieces of iron slag appeared in an unstratified context nearby. A further fulacht fia was found just 35 metres to the south and was excavated at the same time, suggesting this stretch of low-lying ground beside a small stream was a place people returned to repeatedly. Part of the original mound extended beyond the excavation boundary and remains undisturbed in the ground.