The only record of its existence comes from a single aerial photograph taken in January 1984, when melting snow settled unevenly across the field and, in doing so, traced the faint outline of something underneath. The differential melt, caused by buried or disturbed ground retaining heat or moisture differently from the surrounding soil, briefly made visible what centuries of farming had otherwise erased from the surface.

Circular enclosures of this kind are among the most common archaeological features in Ireland, most often associated with early medieval settlement. A ringfort, to use the familiar term, typically consisted of a raised earthen bank enclosing a domestic space, offering a degree of protection and marking out a farmstead. At Knocknaneirk, whatever once stood here left no upstanding trace. The enclosure is described as possible rather than confirmed, because aerial photography alone, particularly from a single oblique or vertical pass in unusual weather, cannot establish with certainty what lies beneath. The 1984 photograph remains the sole piece of evidence.