The story, passed down locally, holds that the animal fell into a cave inside the rath sometime in the 1940s, an incident vivid enough to survive in memory for decades. What the horse had stumbled into was almost certainly a souterrain, an artificial underground passage or chamber typically constructed from stone and used in early medieval Ireland for storage, refuge, or both. These structures were built to be concealed, which is precisely what makes them easy to lose track of over a thousand years.

The rath itself, a ringfort defined by an earthen bank enclosing a roughly circular area, provides the setting. Ringforts were the most common form of rural settlement in early medieval Ireland, and souterrains were frequently incorporated into them, usually accessed from inside the enclosure. By 1975, a formal inspection noted a series of irregularly shaped depressions across the northern interior of this particular rath, ground that had sunk or collapsed unevenly in a way consistent with an underground void beneath. The depressions were interpreted as possible indicators of a souterrain's location, though no excavation appears to have followed to confirm the structure's extent or condition. The horse, in its own way, had provided the earliest modern evidence that something hollow lay beneath the surface.