A barely perceptible rise in the ground marks what was once a horseshoe-shaped mound of burnt material, its opening facing north-west. Around 1977, the mound was levelled, likely in the course of agricultural improvement, and what had survived for perhaps three thousand years was flattened within a season.

The site is a fulacht fia, a type of prehistoric cooking place found in enormous numbers across Ireland. The typical arrangement involved a trough filled with water, heated by dropping fire-cracked stones into it until the water boiled. The spent stones were discarded beside the trough over successive uses, gradually building up the distinctive horseshoe-shaped mound that, at Glennamucklagh, was still recognisable until the late twentieth century. Fulachtaí fia are most commonly associated with the Bronze Age, though their precise social function remains debated; cooking for hunting parties, communal feasting, and even industrial processes such as textile preparation have all been proposed. What makes the Glennamucklagh example quietly melancholy is not its destruction, which was commonplace as land was improved across Ireland during the twentieth century, but the fact that local knowledge kept its shape and orientation alive even after the physical form had gone.