It measures roughly six metres north to south and five metres east to west, more sharply defined on its eastern side than its western, where the profile is noticeably flatter and less pronounced. Most people would walk past it without a second glance. What it represents, however, is a cooking technology that was repeated across this island in enormous numbers during the Bronze Age, and possibly beyond.

This is a fulacht fia, a type of site found in the hundreds across Ireland and thought to represent a prehistoric outdoor cooking place. The typical arrangement involved a trough, often timber-lined, filled with water, and a nearby hearth where stones were heated and then dropped into the trough to bring the water to a boil. The accumulating pile of heat-shattered, burnt stone that built up over repeated use is precisely what gives a fulacht fia its characteristic horseshoe or kidney shape. The mound at Thomastown Demesne fits this pattern closely. A land drain running along a field boundary some nine metres to the west may, in fact, follow the course of a natural watercourse that once made this precise spot convenient for that kind of activity. That proximity to water is almost always a feature of these sites. Intriguingly, bronze implements have been recovered from within the same townland and are held by the National Museum of Ireland, suggesting the wider landscape here was actively used during the Bronze Age. An enclosure of some kind also survives approximately two hundred metres to the north, hinting that the area was not simply passed through but settled, or at least repeatedly returned to.