What looks, at a glance, like scorched earth or agricultural debris is in fact the exposed edge of a fulacht fia, a kind of ancient cooking or processing site typically comprising a mound of fire-cracked stones accumulated beside a trough dug into the ground. The stones would be heated in a fire and dropped into the water-filled trough to bring it to a boil, a slow but effective method that left behind enormous quantities of shattered, heat-stressed rock. Thousands of these sites survive across Ireland, yet each one tends to announce itself quietly, without ceremony.

The clue at Shanacrane is the burnt material visible in section where a field boundary was cut through, exposing a slice of the buried deposit. Nearby, a spring to the north-east almost certainly explains why the site was established here in the first place. Fulachtaí fia are consistently found close to reliable water sources, and a natural spring would have provided exactly the kind of steady, accessible supply the process required. The pairing of scorched stone mound and adjacent water source is so characteristic that the spring's presence helps confirm what the burnt layer alone might only suggest.