Measuring roughly eight inches in length, this mysterious marking caught the attention of M. R. Colhoun in 1945, who noted that the heel portion seemed to have been formed by a cupmark, one of those circular depressions often found carved into stones throughout Ireland's prehistoric landscape. The stone had been incorporated into the bridge's construction, built right into the top of the structure's western wall.

Today, visitors to this quiet spot near the Donegal coastline won't easily spot this intriguing piece of rock art. The stone has either vanished entirely or lies hidden beneath a layer of plaster that now covers parts of the bridge. The surrounding area remains much as it likely was centuries ago; flat grazing land stretches towards the nearby seashore, creating a peaceful rural scene typical of this part of Ireland's rugged northwest.

This footprint stone represents just one small piece of Donegal's rich archaeological tapestry, documented as part of the comprehensive Archaeological Survey of County Donegal compiled in 1983. Whether the marking was genuinely prehistoric, perhaps linked to ancient rituals or territorial markers, or simply a later creation incorporated into local folklore, its disappearance adds another layer of mystery to Ireland's already enigmatic collection of carved stones and rock art.