Only the dark, burnt material beneath the turf, accumulated over centuries of use and now levelled flat, betrays the site for what it is: a fulacht fia, one of the most common yet least understood monument types in the Irish landscape.

Fulachtaí fia are prehistoric cooking sites, typically found close to a water source such as a stream or marshy ground. The usual method involved heating stones in a fire and dropping them into a water-filled trough, bringing the water to a boil. The stones, cracked by the repeated thermal shock, were discarded into a mound around the trough, which is why these sites so often survive as horseshoe-shaped spreads of dark, burnt material. Most examples found across Ireland date broadly to the Bronze Age, though some have yielded evidence of use across much longer spans of time. The Garranes example sits beside a stream, exactly the kind of location these sites favour, though its surface has been levelled and the surrounding land long since brought into agricultural use, leaving no visible mound or distinctive shape to mark it out.