What makes it quietly puzzling is not the mound itself but the ground it stands on: land that was once a lake. Lough Iron has been drained and its bed absorbed into the surrounding landscape, taking with it whatever context once made sense of this feature.

The mound first surfaces as a notation on a sketch map held in the National Museum of Ireland's archives, where it was recorded in the townland of Tristernagh Demesne. Its exact nature remains uncertain. It may be a low cairn, a type of mounded structure often associated with burial or ritual use, or it could be something closer to a crannog, the artificial or artificially modified island platforms built on Irish lakes from the prehistoric period through to the early medieval centuries and typically used as defensible dwelling places. Aerial imagery shows a small circular, tree-covered rise that sits where Tristernagh Island once appeared on the 1837 edition of the Ordnance Survey six-inch map, positioned at the southern end of Lough Iron, roughly 120 metres east of the Tristernagh Demesne shoreline. That island, and whatever stood on it, effectively became landlocked when the lake was drained and the land reclaimed. Adding to the interest of the location is its proximity to Tristernagh monastery, the remains of which lie approximately 450 metres to the south-west. Whether the mound has any relationship to that ecclesiastical site is unknown, but the clustering of features in this small area of mid-Westmeath suggests a landscape that was once considerably more layered than it now appears.