Roughly twelve metres across and filled with dark brown soil and fragments of burnt stone, it looks, if anything, like a slight irregularity in the ground, the kind of thing a farmer might walk past daily without a second thought. It is, in fact, the remains of a fulacht fia, one of the most common yet persistently mysterious monument types in the Irish archaeological landscape.

Fulachtaí fia are found in their thousands across Ireland, most of them dating to the Bronze Age, roughly 2000 to 500 BC. The defining feature is a mound of fire-cracked stone, the discarded debris of repeated heating. The most widely accepted interpretation is that these were cooking sites: stones would be heated in a fire and dropped into a water-filled trough, bringing the water to a boil quickly and efficiently enough to cook meat. The dark, organically rich soil typical of these sites, visible here at Coolcarron, is a product of that sustained burning and the decomposition of organic material over millennia. Some researchers have proposed alternative uses, including textile processing or even bathing, and the debate has not been fully settled. What is consistent across sites is the burnt stone, the waterlogged or low-lying location, and that characteristic dark earth, all of which are present at Coolcarron in their quiet, unassuming way.