It measures nine metres long, seven metres wide, and stands only about sixty centimetres high, modest enough to be easily overlooked. What it represents, however, is a cooking technology that was repeated across the Irish landscape for well over a thousand years during the Bronze Age.

A fulacht fia, sometimes called a burnt mound, is the accumulated debris of an ancient outdoor cooking method. The typical process involved heating stones in a fire and then dropping them into a water-filled trough to bring the water to a boil. The stones, cracked and blackened by repeated heating, were raked out and discarded after each use, and over time these rejected fragments built up into the characteristic horseshoe or kidney-shaped mounds that survive today. The boggy, waterlogged ground at Glynn would have been well suited to the purpose, providing a ready source of water close at hand. This particular mound is not an isolated find but one of a cluster of four fulachta fiadh in the immediate area, with a closely related example sitting just to its west. The concentration suggests the spot was returned to repeatedly, perhaps over several generations, by communities who found the location reliable and convenient.