It measures eight metres in length and just 0.6 metres in height, with an opening of roughly 2.2 metres facing northwest. To the untrained eye it might read as nothing more than a slight rise in scrubby terrain. What it actually represents is one of the most common yet least understood monument types in the Irish landscape.

This is a fulacht fia, a class of prehistoric cooking or processing site found in enormous numbers across Ireland, with County Cork alone accounting for thousands of examples. The structure is characterised by that distinctive horseshoe or kidney shape, formed from the accumulated debris of repeated burning. The typical method involved heating stones in a fire, then dropping them into a water-filled trough to bring the water rapidly to the boil. The stones shatter and blacken with repeated use, and over time the discarded fragments build up into the mound that survives today. The Ballynaraha example follows this pattern closely, its burnt material compacted into a form that has endured long enough to be recorded in the Archaeological Inventory of County Cork, published in 1997. The proximity to a stream is entirely characteristic; a reliable water source was a basic requirement, and fulachta fiadh are found near rivers, streams, and boggy ground with striking regularity throughout the country. The date of construction is not specified for this particular site, but the monument type spans broadly from the Bronze Age onward.