A fulacht fia, roughly translated as a cooking pit or wild deer roast, typically consists of a horseshoe-shaped mound of burnt and fire-cracked stone surrounding a trough that was once lined with wood or clay. The working theory, supported by experimental archaeology, is that stones were heated in a fire and then dropped into water held in the trough, bringing it rapidly to a boil. The mounds of discarded, heat-shattered stone that remain are the enduring signature of this process, sometimes preserved for three thousand years or more.

Most fulachtaí fia date to the Bronze Age, roughly 1500 to 500 BC, though some may be earlier or later. They tend to cluster near water sources, streams and boggy ground, which would have supplied the volume of water the process required. County Clare has a considerable number of recorded examples, and the Aglish site sits within a landscape that has yielded other traces of prehistoric activity. The townland name Aglish derives from the Irish eaglais, meaning church, suggesting later ecclesiastical significance in the same area, though the fulacht fia itself predates any such association by many centuries.