Yet beneath that ordinary surface, excavation work revealed a spread of decaying stones mingled with charcoal and blackened soil, the quiet signature of a fulacht fia, one of the most common and most debated archaeological monuments in Ireland.

A fulacht fia is essentially a prehistoric cooking site, or at least that is the most widely accepted interpretation. The typical arrangement involves a mound of fire-cracked stones beside a trough that would have been filled with water and heated by dropping in stones from a fire. The Coolbaun example came to light not through targeted research but through the practical mechanism of a planning application: archaeological testing of the site was carried out in compliance with the application, and the spread of stones, charcoal, and darkened earth emerged during that work. The excavator interpreted the remains as a fulacht fia, with the findings reported by Pollock in 1998 and again in 2000. The field had already been reclaimed by the time of the investigation, meaning the original monument had no visible surface presence and might never have been identified outside of a formal archaeological examination.