Local tradition holds that a souterrain lies underground here, one of those dry-stone lined tunnels built in early medieval Ireland, typically used for cold storage or as a refuge in times of danger. The knoll itself sits in the middle of a flat, boggy expanse of pasture, and at ground level there is nothing visible to suggest anything lies beneath it. No opening, no depression, no sign of disturbance. The place keeps its secret well.

The site is associated with an earth and stone bank running roughly east to west, about nineteen metres long and four and a half metres wide, known locally as the "moat". Despite the name, this is likely the remnant of an early enclosure rather than anything to do with water, the word reflecting the common Irish habit of applying "moat" loosely to any ancient earthwork. Local memory connects the underground passage to the 1798 Rebellion, the uprising against British rule that convulsed much of Connacht during the summer of that year, when such a concealed space might genuinely have offered shelter to those in hiding. Whether that memory preserves a real use or is an embellishment layered onto an older structure is impossible to say. What is known is that a local landowner named James Henry is said to have opened or explored the souterrain in 1910, though whatever he found, or whether he found anything at all, appears not to have been recorded in any detail that has survived.