A fulacht fia, the term used for a type of prehistoric burnt mound associated with outdoor cooking or heating water, typically survives as a low, horseshoe-shaped rise of fire-cracked stone in wet or boggy ground. The Coolgarriv example was no exception in its setting, occupying marshy pasture before development overtook it, but excavation revealed an unusual layered complexity.

When archaeologists excavated the site ahead of construction, they found a roughly square mound of about eight metres across and only forty centimetres high, built up from six distinct layers of burnt material. On its eastern side sat a recut oval trough, approximately two and a half metres by just under two metres and forty centimetres deep, which still held waterlogged fragments of wood, likely the remnants of a wooden lining or container. The trough being described as "recut" suggests the site was used on more than one occasion, the hollow dug out afresh as it silted or collapsed. Traces of a possible stone kerb around the mound's edge were also identified. Thirteen metres to the north, excavators uncovered a stone trackway, and nearby they found two separate pockets of burnt fulacht fia material, one of which had been deposited directly on top of the trackway itself. These deposits appear to represent material that was cleared or shifted from the main mound at some point, evidence of the site being managed or reorganised rather than simply abandoned. The excavations were carried out and reported by Kiely in 2001, with Dennehy also contributing findings on the trackway. Nothing of the site is visible today.