These are the remains of ancient outdoor cooking places, typically Bronze Age in date, consisting of a trough dug into the ground, a hearth, and a horseshoe-shaped mound of fire-cracked stone and charcoal built up over repeated use. The method was straightforward: stones were heated in a fire and dropped into a water-filled trough to bring it to a boil, enough to cook meat wrapped in straw or carried in a wooden vessel. Thousands of these sites survive across Ireland, often in low-lying or marshy ground where water was reliably close to the surface.

The Rinmore example sits within a broader landscape that has seen continuous human activity across millennia, and the presence of a fulacht fia here suggests that the peninsula's margins, likely wet and well-watered, were attractive to Bronze Age communities going about the ordinary, practical work of preparing food. Most fulachtaí fia date to roughly 1500 to 500 BC, though some are earlier, and the sheer number of them across the country points to a technology that was genuinely useful rather than ceremonial. Some archaeologists have proposed alternative uses, including brewing or textile processing, though cooking remains the most widely accepted interpretation. The mound itself, the burnt spread visible at many such sites, is essentially the accumulated debris of those repeated firings and water-heatings, discarded to the side after each use.