On a steep north-west-facing slope at Knockavannia in County Waterford, a kidney-shaped mound of broken and burnt stone sits quietly in the grass, its irregular outline hinting at a very particular kind of ancient industry. The mound measures roughly 20 metres along its north-west to south-east axis and just over 16 metres across, rising from about 0.7 metres at its upslope, south-eastern edge to a more substantial 2.4 metres at the north-western end, open to the south-west. That asymmetry is not accidental; it reflects centuries of material accumulating in one direction as the mound was built up from repeated use.

This is a fulacht fia, a type of site found in great numbers across Ireland, most commonly dating to the Bronze Age, though some continued in use into the early medieval period. The name, loosely translated from Irish, is traditionally associated with cooking places used by roving hunters or warriors, though archaeologists have long debated their precise function. The typical arrangement involved a trough, often timber-lined, filled with water, into which stones were heated in a nearby fire and then dropped to bring the water to a boil. Over time, the spent, shattered stones were raked out and piled to the side, gradually forming exactly the kind of low, horseshoe or kidney-shaped mound seen here. The burnt, fractured character of the stone is the giveaway, and it is what distinguishes these mounds from natural or agricultural features in the landscape.