It measures roughly nine metres long and ten metres wide, rising only about sixty centimetres above the surrounding ground, with its wide western opening facing towards the water. It is, by any external measure, unassuming. But what it represents is one of the oldest and most widespread forms of cooking technology in prehistoric Ireland.

The site belongs to a class of monument known as a fulacht fia, the remains of a prehistoric outdoor cooking place. The basic principle involved heating stones in a fire, then dropping them into a water-filled trough to bring the water rapidly to the boil. The burnt and shattered stones, discarded after repeated use, accumulated beside the trough over time to form the characteristic horseshoe or kidney-shaped mound that survives today. These features are found in enormous numbers across Ireland, often positioned close to streams or marshy ground where water was readily available, and this example at Caherdrinny fits that pattern precisely. Most fulachtaí fia date to the Bronze Age, roughly 2000 to 500 BC, though some have produced later dates. The accumulation of cracked and blackened stone is the defining signature, and the mound here, ten metres across at its widest, suggests repeated and sustained use over a considerable period.