It is, in all likelihood, a fulacht fia, one of the most common prehistoric monument types in Ireland, and one of the least understood. These horseshoe or kidney-shaped mounds are the accumulated debris of ancient cooking sites, built up over repeated use from fire-cracked stones that were heated and then dropped into water-filled troughs to bring them to the boil. Thousands survive across the country, most of them dating to the Bronze Age, and this one at Rusheens is a quiet, unassuming example of that widespread but still puzzling tradition.

The mound measures 21.5 metres on its north-east to south-west axis and 12 metres across, rising to a height of 0.85 metres. Its kidney shape is well preserved, with a slight indentation along the northern side, the kind of dip that often marks where the trough or working area once sat. At the north-eastern end there is a hollow of roughly four metres by three, and a shallow depression of about three metres in diameter at the south-south-west. Both of these irregularities may reflect relatively recent disturbance rather than any original feature of the site. A field drain runs immediately to the south-east, a reminder that these monuments almost always appear near water, which was essential to their function. The surrounding land is low-lying and has been improved for agricultural use, meaning the mound has survived as something of an accidental remnant in an otherwise heavily managed landscape.