They appear as low, horseshoe-shaped mounds, typically found near water, and are thought to represent ancient cooking sites, though their precise purpose has generated considerable debate among archaeologists. The standard interpretation holds that stones were heated in a fire, then dropped into a water-filled trough to bring it to the boil, with the cracked and shattered stone gradually accumulating into the mound that survives today. The one at Ballygriffy, in County Clare, is one such site, quietly present in the landscape long after the people who used it have left no other trace.

Fulachtaí fia date most commonly to the Bronze Age, broadly spanning from around 2500 to 500 BC, though some sites have produced dates outside that range. County Clare has a notable concentration of them, partly a reflection of the county's boggy and waterlogged terrain, which both suited the original function of these sites and helped preserve the organic material within the mounds over millennia. The name itself, sometimes translated loosely as "cooking place of the deer" or associated with the Fianna of Irish mythology, remains contested, and many archaeologists now simply use the term burnt mound to sidestep the ambiguity. Beyond the cooking hypothesis, alternatives have been proposed over the years, including use as saunas, dyeing vats, or brewing vessels, and it is possible that different sites served different purposes at different times.

The Ballygriffy site sits within a wider rural landscape that repays careful attention on foot, where the low profile of a fulacht fia can be easy to walk past without recognising it for what it is. The characteristic dark, charcoal-flecked soil and the fractured, fire-reddened stones within the mound are the details most worth looking for, modest in appearance but carrying the residue of repeated use across what may have been many generations.