It is made almost entirely of burnt material, the accumulated debris of repeated ancient cooking, and it measures roughly nineteen metres along its longer axis and just over thirteen metres across. This is a fulacht fia, a type of prehistoric cooking site found in enormous numbers across Ireland, typically beside water and in low-lying, sometimes waterlogged ground. The basic method involved heating stones in a fire until they were intensely hot, then dropping them into a water-filled trough to bring the water to a boil. The cracked and shattered stones, useless after a single heating, were thrown aside, and over time those discarded fragments built up into the characteristic mound that survives today.

The horseshoe shape is typical of the form. The open end, here facing north-west, marks where the trough would have sat, with the mound wrapping around it on the other sides. At the western edge of that opening there is a smaller, circular mound of burnt material, a detail that suggests more than one phase or focus of activity at the site. Fulachtaí fia, as they are known in the plural, are generally dated to the Bronze Age, though some sites show evidence of use across a very long span. They are among the most common prehistoric monument types in Ireland, yet individually they tend to survive as quiet, unannounced features in the landscape, their significance disguised by centuries of vegetation.