At Sonnagh in County Mayo, construction of the N5 Charlestown bypass prompted the excavation of a fulacht fia, one of thousands of Bronze Age cooking sites scattered across Ireland. A fulacht fia typically consists of a horseshoe or crescent-shaped mound of fire-cracked stone accumulated beside a water trough, the working debris of repeated cycles of heating stones in a fire and dropping them into water to bring it to the boil. What makes Sonnagh IX, as this particular site was designated, worth pausing over is the detail preserved within it, detail that carries you quite close to the people who actually used it.

The site sat on the eastern edge of a peat basin, flanked by higher, drier ground to north and south, a placement that was almost certainly deliberate; peat bogs are wet by nature, and access to a reliable water table was essential. The crescent-shaped mound measured eleven metres east to west and nine and a half metres north to south, standing no more than half a metre high, packed with heat-fractured sandstone in a matrix of charcoal and peat. Tucked into a depression on its south-eastern side was an oval trough, cut down through the peat and into the underlying marl specifically to tap the local water table. The trough's construction was careful: two split alder timbers lined the base, and hazel and willow stakes were driven into the marl at the north, south, and north-west ends. The fill contained a dense layer of moss and fragmented hazel wicker rods, which excavators interpreted as the probable remains of a wicker lining used to filter the water. The jawbones of a domestic pig were also recovered from the trough, a reminder that this was a place where animals were butchered and food was prepared. A grey chert blade turned up in the mound itself. Radiocarbon dating of alder charcoal from the base of the trough returned a date of 2134 to 1919 calibrated BC, placing the site firmly in the Early Bronze Age.