This is a fulacht fia, a type of prehistoric cooking site found in considerable numbers across Ireland, typically dating to the Bronze Age. The basic principle involves heating stones in a fire and dropping them into a water-filled trough, bringing the water rapidly to the boil. The mound that remains is the accumulated debris of those spent, shattered stones, discarded after each use. What survives at Formoyle is oval in plan, measuring roughly 9.1 metres north to south and 5.9 metres east to west, rising to about 0.9 metres in height. The burnt stones are still visible in the eastern face of the mound.

The site sits on level, rough, rocky ground just 3.5 metres east of the Caher River, a small watercourse flowing northward, and the proximity to that water source is entirely typical of the monument type. It was noted on Tim Robinson's map of the Burren in 1977, and a few years later Cunningham, recording the site in 1980, described its shape as horseshoe-formed rather than oval, a discrepancy that likely reflects how the mound had settled or eroded by the time each observer visited. Both descriptions point to the same degraded but legible feature. Roughly 210 metres to the north-north-east lies a separate enclosure, suggesting this corner of Formoyle preserves more than one layer of past activity, though the relationship between the two features remains unclear.