When the land was being prepared for planting, the landowner noticed a roughly fifteen-metre by ten-metre deposit of burnt material emerging from the north-facing slope, the kind of dark, charcoal-flecked mound that archaeologists recognise almost immediately as a fulacht fia.

A fulacht fia, sometimes called a burnt mound, is among the most common prehistoric monuments in Ireland, with thousands recorded across the country. The general interpretation is that these sites were used for cooking or boiling water, most likely during the Bronze Age. The typical method involved heating stones in a fire until they were extremely hot, then dropping them into a water-filled trough to bring the water to the boil. The cracked and shattered stones were discarded in a mound nearby, which is precisely what survives at so many sites as that characteristic spread of dark, fire-reddened debris. The Foynes Island example, recorded by Denis Power and uploaded to the archaeological record in August 2011, follows this pattern closely. Its position on a north-facing slope within what became a coniferous plantation means it was effectively obscured from casual observation until forestry work happened to disturb the surface.

Foynes Island is accessible by boat from Foynes on the south shore of the Shannon, though it is not a conventional visitor destination and any access would require advance arrangement with landowners. The burnt mound itself lies within the plantation, so visibility at ground level is limited by tree cover. Anyone with a particular interest in prehistoric sites might look for the characteristic dark, ashy soil and the angular fragments of fire-shattered stone that typify fulacht fia deposits; these are modest features by any measure, easy to overlook without some foreknowledge of what they represent. The north-facing slope location is a reminder that these sites were often positioned close to reliable water sources, and the low, damp ground of such an aspect would have suited that practical requirement well.