The stone is gone, its precise original location uncertain, and what remains of the record amounts to a single old photograph and a set of measurements jotted down by an Ordnance Survey field worker in 1940. That combination of documentation and disappearance gives the site an odd quality: meticulously recorded, yet effectively vanished.

A gallán is the Irish term for a standing stone, one of those solitary upright slabs erected across Ireland from the Neolithic through the Bronze Age, whose original purposes remain debated but likely included territorial marking, memorial use, or alignment with astronomical events. The Knockhowlin example appeared on the 1940 edition of the Ordnance Survey six-inch map, situated just to the south of an east-west road. A photograph published in St Peter's Annual in 1917 shows it clearly: a large, roughly tapering stone, narrower at the base than it becomes higher up, which is an unusual feature since standing stones more commonly taper towards the top. The field measurements taken in 1940 recorded its base at approximately 0.75 metres by 0.9 metres, its upper section at around 0.85 metres by 0.75 metres, and its height at roughly two metres. It was, in other words, a substantial and distinctive stone. At some point between that 1917 photograph and more recent survey work, it was removed, and no record survives of where it went or why.