These horseshoe-shaped mounds of burnt and shattered stone, typically found near water sources, are the remnants of Bronze Age cooking sites, though some researchers have proposed they also served as brewing vats, sweat houses, or dyeing troughs. The example recorded at Toorard in County Mayo is one of countless such sites quietly occupying boggy ground across the west of Ireland, its mound a slow accumulation of fire-cracked rock discarded after repeated heating and quenching over centuries.

The general process behind a fulacht fia was straightforward. Stones were heated in a fire and dropped into a water-filled trough, raising the temperature enough to cook meat or carry out whatever task was at hand. Over time, the thermally fractured stone became useless for reheating and was piled to the side, creating the characteristic crescent shape that survives today. Most fulachtaí fia date to the Bronze Age, broadly between 2000 and 500 BC, though some sites show evidence of use across multiple periods. Mayo, with its abundance of wet lowland ground and blanket bog, is particularly well-furnished with them, and the Toorard site fits a pattern found throughout the province of Connacht.