Cairns of this kind are among the oldest constructed features in the Irish countryside, built variously as burial monuments, territorial markers, or summit landmarks, often during the Neolithic or Bronze Age periods. They can be modest piles barely distinguishable from field clearance, or substantial mounds covering stone-built chambers. Which of these Moorbrook's cairn represents is, at present, difficult to say with any certainty.

The available record for this site is thin to the point of near-silence. The monument is recognised and catalogued, which means it has been noted as archaeologically significant, but the details that would normally accompany such a listing, including any excavation history, precise dimensions, or documentary references, are not currently accessible through published sources. That absence is itself quietly telling. Mayo is a county with an extraordinary density of prehistoric remains, many of them still incompletely documented, and cairns in particular have a habit of sitting unremarked for generations, their origins unexamined, their stones occasionally robbed for walls or roads before anyone thought to record what lay beneath.