This is a fulacht fia, a term used for the scorched, crescent-shaped mounds left behind by Bronze Age cooking or processing sites. The typical method involved heating stones in a fire, dropping them into a water-filled trough to bring it to the boil, then repeating the process until the stones cracked and shattered from thermal shock. Over time, the discarded burnt and broken stone accumulated into the distinctive mound that survives today.

The mound at Rossnanarney measures ten metres in length and six metres in width, rising to about 0.6 metres at its highest point on the north-western side, with the characteristic opening of the horseshoe facing south-west. A secondary mound of burnt material, nearly four metres wide, lies roughly 2.8 metres to its south-west, suggesting the site saw repeated or extended use rather than a single episode of activity. What gives this particular location an added layer of interest is that a second fulacht fia lies approximately 70 metres to the north-east, making this a small cluster of related sites in close proximity to one another and to the stream that would have supplied the water essential to their use. The proximity to running water is no coincidence; virtually every fulacht fia in Ireland sits close to a reliable water source, and the density of these monuments across the Cork landscape points to a Bronze Age world that was far more actively and systematically worked than the empty fields above might suggest.