They appear as low, horseshoe-shaped mounds, typically found near water, and are generally dated to the Bronze Age, roughly 1500 to 500 BC. The leading theory holds that they were cooking sites: stones were heated in a fire and then dropped into a water-filled trough, bringing it rapidly to a boil. Experiments have confirmed this works efficiently, though some researchers have proposed the troughs served other purposes, from textile processing to bathing. The mound itself is the accumulated debris of cracked and fire-shattered stone, discarded after repeated heating cycles.

The example at Kilsarkan in County Kerry sits within a landscape that would have been actively farmed and settled during the Bronze Age, a period when Kerry's river valleys and lower hillsides saw considerable human activity. Kilsarkan is a townland in the Sliabh Luachra area of east Kerry, a region with a notably dense spread of prehistoric monuments. The presence of a fulacht fia here is consistent with the pattern seen across Munster, where these sites cluster along streams and in low-lying, often marshy ground, precisely the conditions that made a reliable water source easy to exploit. Without further excavated detail specific to this site, the date and precise character of the Kilsarkan example remain general rather than established with certainty.