This is a fulacht fia, a form of prehistoric cooking site, typically identified by a horseshoe-shaped mound of fire-cracked stone and charcoal accumulated around a trough dug into the earth. The standard interpretation is that water was heated by dropping stones made red-hot in a nearby fire directly into the trough, bringing it to a boil and sustaining enough heat to cook meat. The sites cluster persistently near water sources, which makes the position here, on the northern side of a stream and in marshy ground, entirely characteristic.

By the time an Ordnance Survey six-inch map was produced in 1940, the location was already being recorded simply as a site of a fulacht fiadh, the older Irish spelling of the term, suggesting some prior recognition of its significance even if the physical remains were already reduced to a scatter of burnt material rather than a well-defined mound. The mound form, where it survives elsewhere, is built up gradually over repeated use, each episode of cooking and stone-cracking adding another layer to what eventually becomes a distinctive raised feature in the ground. At Moanflugh, the spread of burnt material is what remains, the physical trace of those repeated firings preserved in the wet, anaerobic conditions that boggy ground tends to provide.