The apex of what was once an ogee-headed door surround, a pointed arch form common in late medieval ecclesiastical stonework, it shows vine leaves curling from intertwined stems, with a bird at the centre pecking a bunch of grapes. On the opposite side of the finial, a matching bunch of grapes survives, but the bird that should have mirrored the first has been broken away. The slab is less than two-thirds of a metre wide, yet it carries enough detail to place this otherwise modest ruin within a broader tradition of late medieval Irish craftsmanship.

The carving is almost identical to the stonework over the sacristy doorway at St Mary's Abbey on Devenish Island in Co. Fermanagh, a comparison that led the architectural historian Harold Leask to date that motif to the third quarter of the 15th century, suggesting a similar date for Ballygriffin. A comparable carved doorway from the Augustinian abbey of Fertagh in Co. Kilkenny was later removed and inserted into the Church of Ireland building at Johnstown, a reminder of how frequently fine medieval stonework was salvaged and reused rather than left in situ. At Ballygriffin the apex stone was luckier; it remained, propped inside the church adjacent to the south doorway, whose opening was at some point crudely rebuilt. A small square hole in the doorway was noted by White in 1892 and is thought to have held a stoup, a small basin for holy water. The east gable had already fallen entirely by the 1840s, leaving only a grass-covered mound of rubble, and the Ordnance Survey letters record that four windows once lit the interior, two in each side wall, though most of their embrasures are now broken or partially lost. A 17th-century graveslab survives towards the west end of the north wall inside.

The church sits towards the northern end of a rectangular graveyard in flat pasture that slopes gently westward towards the Multeen River valley. Seventy metres to the south stand the remains of Ballygriffin fortified house and its bawn, the enclosed courtyard wall that typically accompanied such tower houses, making this a quietly layered corner of the landscape where a medieval parish church, a defensive residence, and a working graveyard once occupied the same small field.