The site at Coolboy is a burnt mound, a type of prehistoric feature found widely across Ireland and Britain, typically consisting of a mound of fire-cracked stones and charcoal-rich soil accumulated near a water source. The leading theory is that these sites were used for heating water, perhaps for cooking or bathing, by dropping stones heated in a fire into a trough or pit. They are often dismissed as unglamorous, but they are among the most direct traces of everyday life from the Bronze Age that the Irish landscape preserves.

In 1997, archaeologist Brendán Ó Riordáin investigated this particular spread of burnt material as part of excavations carried out ahead of the Arklow bypass road scheme. The deposit was around a quarter of a metre deep when it was recorded. Before the work could be completed, however, the excavation area became flooded, and work was halted. The site was subsequently backfilled and left undisturbed, the mound returned, more or less, to the condition it had been in before the bypass project brought it briefly to light.