It is not the tallest or most dramatic of standing stones, measuring roughly 1.1 metres in both height and width, but its deliberate placement beside what appears to have been the entrance to the enclosure suggests it was never incidental. Someone put it there with intent.

A cashel is a drystone ringfort, a form of enclosed settlement used across Ireland from the early medieval period onwards, and the one at Killaclug still survives nearby. The standing stone, rectangular in plan and slab-like rather than the tapered pillar shape more commonly associated with prehistoric examples, runs parallel to the cashel's western bank. Its proximity to the probable entrance is the detail that draws attention. Stones positioned at or near the thresholds of enclosures are known from other Irish sites, sometimes interpreted as boundary markers, sometimes as something harder to categorise. Whether this one served a practical, symbolic, or ritual purpose is not recorded, and the archaeology does not settle the question.