That kind of cartographic invisibility is unusual for a monument standing over a metre and a half tall, and it raises the obvious question of how a prehistoric marker of this size went unrecorded for so long.

The stone itself measures 1.55 metres in height, with a footprint of roughly 1.57 metres by 0.5 metres, and is subrectangular in plan, meaning it has a broadly rectangular cross-section with slightly irregular edges rather than the rounded profile of a natural boulder. Its long axis runs northwest to southeast, an orientation that recurs often enough among Irish standing stones to suggest it was deliberate, though what exactly it commemorated or marked is unknown, as is typical of this class of monument. What makes the Knockraheen example particularly legible, in a physical sense, is that the packing stones used to wedge and stabilise it in the ground are still visible at the base, a detail that brings the original act of erection unexpectedly close. Someone selected those stones, placed them carefully around the base to hold the upright steady, and left them there.