The Ordnance Survey cartographers who mapped this part of Ireland in 1842 did not mark it, and when the same sheets were revised in 1904, it was absent again. Whether that reflects overgrown ground, a surveyor's oversight, or the stone's modest scale is impossible to say now, but the omission gives it an odd quality: a prehistoric monument that slipped through two rounds of official documentation.

The stone itself is relatively understated. It stands just over a metre tall, measuring roughly 72 centimetres by 47 centimetres at its base, and is subrectangular in plan, meaning its cross-section is broadly rectangular with slightly irregular edges rather than a neat geometric shape. Its long axis runs north to south, an orientation that may or may not be deliberate; many standing stones across Ireland share similar alignments, though the reasons behind individual placements remain largely a matter of informed speculation. Standing stones are among the most elemental of prehistoric monuments, typically single upright blocks set into the ground, probably during the Bronze Age, and interpreted variously as boundary markers, ritual focal points, or memorials. Without excavation or associated finds, the stone at Knocknalyre keeps its own counsel on that question.