The boulder marks the entrance to a souterrain, a type of dry-stone passage or chamber built underground, typically during the early medieval period, and used variously for storage, refuge, or as an escape route from a nearby settlement. This one is now inaccessible, its secrets intact beneath the stone.

The souterrain sits within a univallate rath, a type of enclosed farmstead defined by a single encircling earthen bank, which was the standard form of rural settlement in Ireland roughly between the fifth and twelfth centuries. At Trippul, that bank encloses a sub-circular area, though the site has been cut rather unceremoniously in two by a track running in a north-west to south-east direction. The souterrain entrance lies in the west-north-west sector of the interior, constructed of stone and now sealed beneath its mossy capstone. The site is recorded in C. Toal's North Kerry Archaeological Survey, published in 1995, which documented dozens of such monuments across this part of the county, many of them similarly overlooked or partially disturbed by later land use.

The division of the rath by a track is a telling detail. It is a reminder of how quietly these sites absorbed centuries of agricultural and practical life around them, accumulating small indignities without quite disappearing. The earthen bank is described as low and wide, the kind of feature easily mistaken for a natural rise in the ground, and the souterrain beneath it remains closed, its stone construction preserved but unexamined.