What makes it quietly odd is the layering visible in its own walls: the herringbone-style field walls that define its shape today are relatively modern constructions, yet the northern and eastern sections rest on older double-walling, between 1.3 and 1.7 metres wide, that may date to the medieval period. Whoever built the later walls was, knowingly or not, building on top of something considerably older.

A cashel is a type of stone-walled ringfort, typically circular or oval, built in early medieval Ireland as an enclosed farmstead or settlement. The enclosure at Murrooghtoohy is trapezoidal rather than circular, measuring roughly 23 metres north to south and narrowing slightly from 19 metres at the south to 16 metres at the north, which is part of why it has been catalogued cautiously as an enclosure rather than a cashel outright. Its narrow entrance near the north end of the east wall, just 0.6 metres wide, may itself be a modern addition rather than an original feature. The interior is largely bare outcropping limestone, the Burren bedrock breaking through the surface in the way it does across much of this landscape. About 350 metres upslope to the south-south-east sits a confirmed cashel, and that site looks directly down onto this one, which raises the possibility that the two enclosures were related in some way, perhaps functionally, perhaps simply as neighbours on the same working hillside.