A 1939 Ordnance Survey six-inch map recorded it as a mound, which is the typical surface signature of a fulacht fia, one of the most common prehistoric monument types in Ireland. A fulacht fia is a burnt mound, the accumulated debris of a repeated ancient cooking or heating process in which stones were fired and dropped into a water-filled trough to bring it to the boil. The charred and shattered stones were raked out and piled up, forming a low horseshoe-shaped mound that can persist for millennia. At Barrahaurin, that mound is gone, or at least no longer visible at the surface.

What makes the site quietly curious is precisely this absence. By the time it was formally recorded, the feature that identified it had already vanished. The 1939 map entry became, in effect, the only surviving witness. A second possible fulacht fia lies roughly ten metres to the south, suggesting the area may once have seen repeated or prolonged prehistoric activity of this kind, though that second site shares some of the same uncertainty about what, if anything, remains.