It is a fulacht fia, a type of prehistoric cooking site found in enormous numbers across Ireland, and one of the more quietly remarkable categories of monument the island possesses. The typical fulacht fia consists of a horseshoe-shaped mound of fire-cracked stone surrounding a trough, usually timber-lined and dug into the ground. The working principle was straightforward: stones were heated in a fire, then dropped into the water-filled trough until it boiled, at which point meat could be cooked. Experiments have shown the method is genuinely efficient, bringing a full trough to the boil in under half an hour.

Fulachtaí fia, to use the Irish plural, date mostly to the Bronze Age, roughly 1500 to 500 BC, though some sites have earlier or later phases of use. They tend to cluster near water sources, since a reliable supply was essential to the whole operation, and they are often found in low-lying or marshy ground as a result. Ireland has thousands of recorded examples, making them one of the most common field monuments in the country, yet individually they attract little attention. The Knockerry example is one of Clare's contributions to that count, a county that, like most of Munster, has a particularly dense scatter of these sites across its landscape.