At Gortaclare in County Clare, four of them cluster within a few metres of one another, which is the kind of density that prompts questions about what, exactly, was going on here over a prolonged stretch of prehistory.

A fulacht fia, to use the Irish term, is a prehistoric cooking place, typically consisting of a trough dug into the ground, a fire for heating stones, and water brought to the boil by dropping the hot stones in. The mound that survives above ground is the accumulated debris of those stones, cracked and discarded after repeated heating. The example described at Gortaclare is a small, circular, grass-covered mound, measuring roughly 3.2 metres north to south and 3 metres east to west, rising to about 0.9 metres in height. It sits to the south of a small eastward-flowing stream, on low-lying level pastureland, with a low but steep-sided ridge climbing away to the south. The eastern end of the mound has been overtaken by briar and thorn. Three further fulachtaí fia belong to the same cluster, one lying 10 metres to the north on the opposite bank of the stream, another 5 metres to the west, and a fourth 10 metres to the southwest. Whether the proximity of the stream was the decisive factor in drawing repeated use to this particular spot, as it would have supplied the water essential to the whole process, the grouping suggests activity that was sustained and deliberate rather than casual or one-off.