A fulacht fia, the term used for a type of prehistoric cooking place typically identified by its distinctive horseshoe-shaped mound of fire-cracked stone and charcoal, once occupied a patch of level, poorly drained rough pasture here. By the time archaeologists came to record it, the site was already being consumed by a holiday-home complex, and no visible remains could be found above ground.

These sites are among the most common prehistoric monuments in Ireland, and they tend to cluster where the ground holds water. The method almost certainly involved heating stones in a fire and dropping them into a water-filled trough to bring the water to a boil, whether for cooking, bathing, or other purposes that are still debated. The boggy conditions at Groin would have suited exactly that kind of use. What makes this particular location quietly notable is not the site itself, which is gone, but its immediate neighbourhood. Three further fulachtaí fia lie in close proximity to the north-west, suggesting that this soggy corner of Kerry was returned to repeatedly over time, generation after generation choosing the same waterlogged ground for the same purpose. A drainage ditch running roughly ten metres to the north of the recorded location is the kind of modern intervention that speaks to just how unsuitable this land has always been for conventional farming, which is perhaps precisely why it was never ploughed into obscurity before the holiday homes arrived.