It would be easy to walk past without a second thought. What gives it away, to those who know what to look for, is the shape: a horseshoe of heat-fractured stones, its arms curling around a central hollow open to the east, with rushes growing thickly around the edges and inside the depression itself. This is a fulacht fia, a type of prehistoric cooking site found in enormous numbers across Ireland, typically near water. The working theory is that stones were heated in a fire and dropped into a water-filled trough to bring it to the boil, leaving behind a characteristic scatter of cracked, fire-damaged rock that accumulated over repeated use into exactly this kind of curved mound.

The site at Carrownaraha is modest on its own terms, measuring roughly 5.5 metres east to west and 7.8 metres north to south, and positioned just 13.5 metres west of a stream. That proximity to running water is no accident; fulachtaí fia are almost always found near a reliable water source, and this stream appears to have been a focal point for sustained activity over time. Four more examples lie in the adjacent field to the north, running along the western bank of the same stream, the nearest of them only about 40 metres away. Five fulachtaí fia clustered along a single watercourse suggests this stretch of ground was returned to repeatedly, perhaps across generations, making what looks like an unremarkable boggy corner of a Mayo field something considerably more layered than it first appears.