On the 1904 Ordnance Survey six-inch map, the spot is marked as 'Carrigapoultaluan', a label that turns out to be a fairly precise description of what lies beneath it. O'Donoghue, writing in 1986, translated the Irish as 'Carraig a'Pholl Talmhan', meaning 'rock of the souterrain', and the name has outlasted the structure itself in local memory.

A souterrain is an underground passage or chamber, typically built during the early medieval period in Ireland, usually by lining a trench with dry-stone walls and covering it with large flat lintels to form a roof before back-filling with earth. They served various purposes, most likely storage and refuge. The Cooldaniel example, according to local accounts, was no modest single corridor; there were several chambers, their walls carefully stone-lined and their ceilings formed from the same lintel construction common to the type. Beyond that, the record grows thin. The exact position of the souterrain is no longer known with any confidence, and only a rough sense of where it lies has been preserved through local knowledge.

What remains, then, is essentially a place-name performing the work of archaeology. The landscape at Cooldaniel still holds the Irish word for what was once underfoot, even as the physical structure has receded from view. It is the kind of situation that recurs quietly across rural Ireland, where the map preserves a memory that the ground itself no longer offers up.