They appear as low, horseshoe-shaped mounds, typically dark with charred and shattered stone, and are found most often in low-lying, boggy ground near water. The one recorded at Killeentierna, in County Kerry, is one of countless such sites that survive quietly in the landscape, easy to walk past without a second glance.

A fulacht fia, sometimes translated loosely as a cooking place or burnt mound, is generally understood to be a Bronze Age site used for heating water. The typical method involved heating stones in a nearby fire, then dropping them into a trough of water to bring it to boiling point. The cracked and heat-shattered stones were then discarded to one side, gradually building up the characteristic mound that survives today. Most examples in Ireland date from roughly 1500 to 500 BC, though some are older or later. Their exact purpose has been debated; cooking meat is the most commonly accepted explanation, but experimental archaeology has suggested they could equally have been used for bathing, textile processing, or brewing. Killeentierna itself is a rural parish in the Iveragh peninsula area of Kerry, a landscape that has seen continuous human settlement from the prehistoric period onward, and fulachtaí fia are well represented across the county.