They appear as low, horseshoe-shaped mounds, typically found near water, and are generally dated to the Bronze Age, though some continued in use into the early medieval period. The mound itself is the accumulated debris of repeated use: cracked and fire-shattered stone, dark with charring, built up over generations of heating water by dropping superheated rocks into a trough. The trough, usually timber-lined or cut into the ground, held the water; the stones, once spent, were tossed aside. That simple, repeated action is what created the mound.

The one at Levallinree, in County Mayo, is a quiet example of this widespread prehistoric activity. Mayo has no shortage of them. The county's boggy ground, with its reliable access to standing water and its capacity for preserving organic and stone features alike, proved well suited to whatever purpose these sites served. Archaeologists have long debated that purpose. Cooking is the most widely accepted explanation, supported by experimental archaeology showing that a fulacht fia can bring water to a boil within thirty minutes and sustain a temperature sufficient to cook large joints of meat. Other theories, including bathing, textile processing, and brewing, have also been tested and argued over, and it is quite possible that different communities used them in different ways at different times.

Levallinree itself is a townland in the west of the county, and the fulacht fia recorded there adds one more point to the dense distribution of Bronze Age activity visible across the Irish midlands and west. Without more detailed excavation records available, the site remains one of many, an unassuming rise in the ground that, on closer inspection, carries a few thousand years of domestic or ritual life compressed into blackened stone and peat.