These are crescent-shaped or kidney-shaped mounds of fire-cracked stones, charcoal, and ash, left behind by prehistoric communities who repeatedly heated stones in a fire, then dropped them into a water-filled trough to bring the water to the boil. The practice was common throughout the Bronze Age, roughly 2000 to 500 BC, and the resulting dumps of spent, shattered stone can survive in the ground for millennia. They are sometimes called fulacht fiadh in Irish, though what exactly was being cooked, or whether cooking was always the point, remains a matter of debate among archaeologists.

Burnt mounds tend to cluster near streams or boggy ground, since a reliable water source was essential to the whole operation. Clare has a considerable number of recorded examples, reflecting both the density of Bronze Age activity in the region and the county's abundance of the wet, low-lying ground these sites seem to favour. The Cragbrien example is one among many, catalogued but not yet fully documented in the public record, which means the specific details of its size, condition, and precise location within the townland are not currently available.