It would likely have stayed forgotten entirely had a stretch of the surrounding ringfort not been put to use as a cabbage garden in 1845, at which point the soil gave way to something older. A souterrain, as these dry-stone underground passages are known, was typically constructed in early medieval Ireland for storage, refuge, or both, and this one proved to have been in use long before anyone thought to grow vegetables above it.

When the passage came to light in 1845, several of its roofing lintels, the flat stones laid transversely across the narrowing side walls to form a ceiling, were lifted and stacked on the rampart of the ringfort, apparently with the intention of moving them properly at a later point. One of those lintels, however, never made it to its intended destination. It bore an ogham inscription, ogham being an early medieval alphabet carved as a series of notches along a stone's edge, and word of it reached John Windele, a Cork-based antiquarian with a well-documented appetite for such things. The stone was removed in secret and sold to him for £1. By 1939, when P. J. Hartnett examined what remained, the souterrain's entrances had been blocked and the passage itself had become inaccessible. The ogham stone, at least, made it into the scholarly record, even if the route to it was not exactly straightforward.