The one at Shammerdoo, in County Mayo, is a typical example of a type that is anything but typical in what it implies about prehistoric life. A fulacht fia is generally understood to be a burnt mound, the horseshoe-shaped remains of repeated fire-setting and water-heating activity, most often dated to the Bronze Age. The process involved heating stones in a fire, dropping them into a water-filled trough, and bringing the water to a boil. The cracked and shattered stones were then discarded into a mound around the trough, which is the visible feature that survives today.

These sites appear so frequently across Ireland, and in such varied locations, often near streams or boggy ground, that archaeologists have long debated their primary purpose. Cooking is the most widely accepted explanation, though experimental work has shown the method is equally effective for brewing, textile processing, or bathing. The Shammerdoo example sits within a Mayo landscape that has yielded evidence of continuous human activity from the Neolithic onwards, and its presence there, unremarkable in isolation, is part of a broader pattern of Bronze Age land use across the west of Ireland. The place name Shammerdoo is likely an anglicisation of an Irish original, though without further documentary evidence it is difficult to say more with confidence.