Less celebrated, and easy to overlook entirely, is the fact that the same townland also contains a fulacht fia, a type of site that turns up in considerable numbers across the Irish landscape and yet remains genuinely puzzling to specialists.

A fulacht fia, at its simplest, is a burnt mound, the accumulated debris of a cooking method that involved heating stones in a fire and dropping them into a water-filled trough to bring the water to a boil. The stones crack and shatter with repeated use, building up over time into a distinctive horseshoe-shaped mound of reddened, fire-shattered fragments. Thousands of these sites are known across Ireland, dating mostly to the Bronze Age, though some were used into the early medieval period. They tend to cluster near water sources, bogs, or low-lying ground where a timber or stone trough could be kept filled. Whether they served primarily as cooking sites, as some researchers have argued, or had other functions including bathing or industrial processes such as dyeing or brewing, remains a matter of ongoing discussion. The Gleninsheen example sits within a landscape already known to have been active and significant during the Bronze Age, which gives even a modest earthwork like this a certain weight of context.