That grouping is the detail worth pausing on. A single fulacht fia might be unremarkable; five in the same locality suggests something more deliberate and repeated about how people used this particular patch of ground over a very long stretch of time.

Fulachta fiadh, the plural form, are among the most common prehistoric monuments found across Ireland. The basic principle behind them is well understood: a trough, usually timber-lined or stone-lined, was filled with water, and stones heated in a nearby fire were dropped in to bring it to the boil. The resulting spreads of shattered, blackened stone are what survive, sometimes as low mounds, sometimes, as here, as a flatter scatter of burnt material just visible in cultivated ground. What these sites were actually used for is a matter of ongoing debate; cooking is the traditional explanation, but brewing, hide-processing, and bathing have all been proposed with some seriousness. The Caherduggan example measures seven metres north to south and three metres east to west, dimensions that place it comfortably within the typical range for such sites.