It is not much to look at from above, but what it represents is a recurring feature of the Irish Bronze Age landscape: a fulacht fia, the term used for an ancient cooking or processing site typically identified by a mound of heat-shattered, fire-cracked stones discarded after repeated use.

The site sits approximately thirty metres east of a stream, which is exactly where you would expect to find one. Fulachtaí fia, the plural form, are almost always located close to a water source, and the working theory is that their users would heat stones in a fire, then drop them into a water-filled trough to bring the water to boiling point, using the technique for cooking, brewing, or possibly textile processing. The burnt and broken stones, useless once cracked by the heat, were piled to the side, forming the characteristic horseshoe-shaped mound that survives at many such sites across Ireland. At Knockduff, that mound material is still present, though it lies low and largely obscured. A second fulacht fia sits roughly a hundred metres to the north-west, suggesting this patch of boggy ground was returned to more than once, perhaps across generations.