The one at Lisduff in County Clare is a quiet example of a prehistoric site type that appears so frequently in bogs, river margins, and low-lying wet ground that archaeologists have long debated what exactly these places were for. A fulacht fia, at its most basic, is a burnt mound, typically a horseshoe-shaped heap of fire-cracked stones accumulated beside a trough cut into the earth. The prevailing interpretation is that stones were heated in a fire and then dropped into a water-filled trough to bring it to the boil, making these sites a form of prehistoric cooking place, though theories about their use for brewing, bathing, or textile processing have also been seriously entertained.

The date range most commonly associated with fulachtaí fia runs from the Bronze Age, roughly 1500 BC, into the early medieval period, making them a feature of Irish life across an enormous stretch of time. The mounds themselves are formed from the discarded stones, shattered by repeated heating and cooling, which accumulated over many episodes of use. Because they tend to survive in damp or marginal ground where later agriculture disturbed them less, they are often found intact enough to excavate, and many have yielded wooden troughs, stakes, and the remains of hearths. The Lisduff example sits within a county that has a considerable density of prehistoric monument types, from the limestone karst of the Burren to the lake-fringed lowlands further east, environments that would have supported the kind of waterside activity a fulacht fia requires.