The site at Ballynattin yielded what appears to be a fulacht fia, along with slot-trenches, pits, and post-holes, all of which point to sustained human activity at some point in the prehistoric past.

A fulacht fia is a type of cooking or processing site found widely across Ireland and Britain, typically consisting of a trough, once filled with water, and a mound of heat-shattered stone formed by repeatedly heating rocks in a fire and dropping them into the water to bring it to a boil. They are most commonly associated with the Bronze Age, though the precise purposes they served remain debated, with theories ranging from food preparation to bathing or textile working. The Ballynattin example was excavated in 2003 under licence, in advance of the Arklow IDA Enterprise Park development, and documented by Tierney in 2006. The accompanying slot-trenches and post-holes suggest structural activity nearby, though the full picture of what stood here and who used it remains incomplete. The designation of the fulacht fia itself as "possible" reflects the difficulty of identifying such sites with certainty once the characteristic mound of burnt stone has been disturbed or dispersed over time.