It is easy to miss, and the records are careful not to overstate it, noting only that the hollow may indicate a souterrain, an underground passage or chamber, typically dry-stone lined, built during the early medieval period and used variously for storage, refuge, or ventilation within a settlement.

The cashel itself, a type of circular stone-walled enclosure common across early medieval Ireland and used to define and protect a farmstead or small settlement, sits within an area surveyed in 1994 by D. Lavelle as part of a local archaeological study covering Ballinrobe and the districts around Lough Mask and Lough Carra in County Mayo. That survey, running to detailed site-by-site assessments, flagged this particular feature at entry number 548. The language of the record is deliberately cautious. A depression in the ground is not a confirmed souterrain; it is a possibility, a surface trace that warrants attention but cannot, without excavation or more detailed investigation, be stated with certainty. That kind of qualified observation is itself revealing, since it reflects how much of early medieval Ireland remains known only through crop marks, hollow ground, and the patient reading of disturbed earth.