They appear as low, horseshoe-shaped mounds, typically found near water, and are thought to date mainly from the Bronze Age, roughly 1500 to 500 BC. The name, sometimes translated loosely as "cooking place of the deer", points to one long-held theory about their purpose: that they were used for boiling water by heating stones in a fire and dropping them into a water-filled trough. The stones crack and shatter with repeated use, and it is this accumulated pile of burnt, fragmented stone that forms the mound a walker might notice today, often blackened and mixed with charcoal.

The example recorded near Cashel in County Mayo sits within a landscape that has seen continuous human activity since prehistory. Mayo's boglands have proved particularly good at preserving such sites, sometimes sealing the wooden troughs and associated timbers beneath layers of peat that formed over millennia. The precise details of this particular site remain sparse in the available record, but its presence near Cashel adds to a broader pattern of Bronze Age activity across the west of Ireland, where fulachta fia cluster near rivers, streams, and marshy ground, suggesting communities that returned repeatedly to the same reliable water sources. Some researchers have proposed alternative uses beyond cooking, including textile dyeing, hide preparation, or even bathing, though no single theory has won universal acceptance.