It is easy to miss, and easier still to misread; it looks, at a glance, like a natural rise in the rough grazing land. But the blackened, heat-shattered stones and the charcoal-dark soil underneath tell a more deliberate story.

This is a fulacht fia, a type of prehistoric cooking site found in large numbers across Ireland, particularly in low-lying or boggy ground. The typical method involved heating stones in a fire until they were intensely hot, then dropping them into a water-filled trough to bring the liquid to a boil. The stones shattered with the repeated thermal shock, and over time the discarded fragments accumulated into the horseshoe or crescent-shaped mounds that survive today. The example at Derreenataggart measures roughly 8.3 metres north to south and 6 metres east to west, rising only about half a metre above the surrounding ground. Its opening, 1.3 metres wide, faces west towards boggy ground, which is characteristic: proximity to a reliable water source was essential to the whole process. Thousands of fulachtaí fia have been recorded across Ireland, and while their precise function is still debated, cooking, bathing, and textile processing have all been proposed by researchers over the years.