It measures roughly six metres north to south, four metres east to west, and rises about a metre above the surrounding rough grazing. What makes it more than a curiosity of the landscape is what it is made of: burnt material, the compacted residue of repeated, ancient heating. Where the nearby stream is cutting into its western and south-western edges, that scorched interior is laid bare.

This is a fulacht fia, a type of prehistoric cooking or processing site found in considerable numbers across Ireland, particularly in low-lying or waterside locations. The typical arrangement involved heating stones in a fire, then dropping them into a water-filled trough to bring the water to a boil; the cracked and shattered stones were then discarded into a mound nearby. Over time, and through repeated use, these discarded stones accumulated into the characteristically horseshoe or D-shaped mounds that survive today. The form seen here at An Gabhlán Beag follows that pattern closely: the straight western face of the D would have been the working side, positioned close to the stream that provided both water and, eventually, the erosive force now gradually dismantling the mound's edge. Most fulachtaí fia date to the Bronze Age, though the term itself is medieval Irish, meaning roughly "cooking place of the deer" or "cooking place of the wild", and the sites were already mysterious to later inhabitants who gave them their name.