The souterrain at Ballyhomulta, running roughly five metres along a north-south axis, survives in fragments: a roof lintel pressed flush with the ground marks its southern extent, and another lintel, just under a metre wide, sits 2.8 metres further north, still supported by corbels. A souterrain is a stone-lined underground passage, typically associated with early medieval settlement, likely used for storage or refuge. From that second lintel, a roofed section of the passage stretches approximately 2.2 metres northward before reaching what was once the backwall.

That northern end is where the structure gets interesting. The backwall has collapsed, at least partly, and beyond it something that looks very much like an animal den has made use of the void. A cavity in the outer face of the inner bank of the surrounding rath, in a poached and churned patch of ground, may be the den's other entrance, measuring about 2.15 metres in length. The rath itself, a ringfort defined by an earthen bank and ditch, would once have enclosed a farmstead, likely from the early medieval period. The souterrain sits in the northern sector of the rath's interior, precisely where such features are commonly found, integrated into the defensive architecture of the enclosure. What was engineered as a deliberate human space has quietly been repurposed, its collapsed northern end now serving as a burrow, the ancient stonework providing shelter for something altogether less historical.