The site is classified as an anomalous stone group, a category that tends to describe arrangements of standing stones or boulders that do not fit neatly into the recognised typologies of prehistoric monuments. What makes Derrycool quietly puzzling is not what survives but what does not: there is no visible surface trace remaining, just open farmland with good sightlines to the south and north.

The main clue to what once existed here comes from the first edition Ordnance Survey map, which labels the spot as a cromlech. That word, borrowed into English from Welsh, was used by early nineteenth-century surveyors and antiquarians as a loose term for megalithic structures, often what we would now call a portal tomb or dolmen, typically a large capstone balanced across upright supports. The Ordnance Survey mapmakers of that era were not always consistent in their terminology, and the notation at Derrycool came with no accompanying description in the survey documents, leaving the precise nature of the feature unrecorded. Whatever stood or lay here when the first edition maps were being drawn, it left no further paper trail, and at some point between that survey and the present, it disappeared from the ground entirely, likely disturbed or cleared during agricultural activity.