It measures 85 centimetres tall by 75 centimetres wide, and it depicts a heraldic shield flanked by fantastical creatures: on the left, a cockatrice with wings raised, and on the right, a horse that may be intended as Pegasus. Above the shield sits a coronet, and at the very top, the raised initials R N and I P are still legible. Beneath the shield, a floral motif winds across the stone. The whole thing is a 17th-century armorial plaque, and it is considerably older than the bridge wall in which it now sits.

The initials belong to Richard Nugent, Baron of Delvin and first Earl of Westmeath, and his wife Jane Plunkett, daughter of Christopher, 9th Lord of Killeen. The shield is divided to show both family lines: the Nugent arms on the left, featuring ermines and two horizontal bars, and the Plunkett arms on the right, with a diagonal strap, known in heraldry as a bend, alongside a castellated tower. The earldom of Westmeath was created in 1621, Richard Nugent died in 1641, and Jane Plunkett followed in 1643. On the lower right of the plaque, the incised numerals 43 survive, likely the remnant of the date 1643, though the 16 that would have appeared on the lower left is no longer visible. The plaque may have been carved to mark Jane Plunkett's death, or it may relate to an eastward extension of the medieval bridge that once stood here. A medieval castle stood in a field roughly 45 metres to the east of the bridge, suggesting the crossing was already part of a significant local complex long before the Nugents had it commemorated in stone.

The plaque is visible on the bridge at Finnea, incorporated into the parapet wall on the western face of the eastern section. It is easy to pass over entirely if you are not looking for it, set as it is into fabric that reads as ordinary 19th-century bridge construction. The cockatrice, a creature from medieval heraldry combining the features of a rooster and a serpent, is worth examining closely alongside the partial date, which quietly anchors the stone to a specific, recoverable moment in the 1640s.