In 2006, ahead of the M8/N8 Cullahill to Cashel Road Improvement Scheme in County Kilkenny, excavators uncovered a fulacht fia, one of the low, horseshoe-shaped mounds of fire-cracked stone that are among the most common prehistoric monuments in Ireland. A fulacht fia is essentially the debris of repeated water-boiling: stones were heated in a fire, then dropped into a trough or pit filled with water to bring it rapidly to temperature, and the shattered, blackened fragments were raked aside over time, accumulating into the distinctive dark mound. The purpose of all this heating is still debated; cooking meat is the traditional explanation, but brewing, textile processing, and bathing have all been proposed.

The mound at Islands sat in a marshy field on the edge of wetlands, exactly the kind of waterlogged ground these features tend to favour. It measured roughly 13.5 metres north to south and 19 metres east to west, composed of black sandy silt packed with broken angular burnt stone, and extended eastward beyond the limits of the excavation. A few metres to the north lay a suboval pit, about 2.35 by 1.81 metres, with vertical sides, a flat base, and two post-holes set into it, suggesting some kind of wooden lining or superstructure. A modern field drain had cut across the mound east to west, a small indignity from a much later era of land management. What makes the site particularly interesting is a chronological gap in its use. Radiocarbon dating placed the mound itself between approximately 1610 and 1410 BC, in the middle Bronze Age, while the pit returned a later date of 1060 to 840 BC. Whether those two features represent a continuous but intermittent use of the same location, or two separate episodes of activity generations apart, is difficult to say from the physical evidence alone, but the site was clearly returned to long after the original mound had been built up.