The site is a fulacht fia, a type of prehistoric cooking place found in great numbers across Ireland, typically consisting of a horseshoe-shaped mound of burnt and cracked stone beside a trough that would have been filled with water and heated using fire-warmed stones. This particular example came to light not through planned excavation but through the progress of a gas pipeline.

When the Cork-Dublin gas pipeline was being laid between 1981 and 1982, the route cut through this part of east Cork and levelled the mound entirely. A partial excavation, documented by Sleeman and Verling in 1987, recorded what remained before it was gone. The mound had reached approximately two metres in depth, which suggests a site of considerable accumulation, the result of repeated use over time as spent, shattered stones were piled up after each heating. The date of the original activity is not specified in the available record, though fulachta fia are most commonly associated with the Bronze Age, roughly 2000 to 500 BC. The site at Walshtown Beg now exists only in that 1987 report and in the county inventory; on the ground, there is nothing left to see.