The ruin is known as Templenamarve, a name that appears on the Ordnance Survey six-inch maps, and it occupies an unusually exposed position for a place of worship, close enough to the water that storm damage to its walls would surprise no one. What makes it stranger still is the density of architectural detail that survives despite that exposure: two doorways, multiple window embrasures, the ghost of a northern aisle, a sacristy, and, set into the eastern gable, a carved stone depicting what a recorder has described, with some dry humour, as resembling two stone balls, or what the Spanish might call conjones, framed with a moulded border and reused from some earlier, unknown context.

The antiquary Thomas Westropp, writing between 1900 and 1902, dated the church to the late medieval period, probably the fifteenth century. It is a single-cell building combining nave and chancel, though it once had a northern aisle and a sacristy on the north side of the chancel, neither of which survives intact; only a scar in the wall betrays where the aisle was bonded. The walls are built of small facing stones with a rubble core, rising to an internal string course and a secondary parapet of even smaller stones above. Particularly fine is the western doorway, where alternating courses of Old Red Sandstone and Dundry stone, the latter a distinctive oolitic limestone quarried near Bristol and exported widely to Ireland during the medieval period, are laid in a deliberately decorative pattern. The eastern wall, which alone has a base batter, a sloping thickening at the foot to add stability, contains a twin-light lancet window whose central mullion is now missing; its pointed embrasure is dressed with a triple roll-moulding, and two decorative buttresses on the exterior are arranged so that the window appears centred between them, though it is not actually centred on the wall itself. Those buttresses echo the design of the nearby cathedral, just 110 metres to the northwest, suggesting the two buildings were conceived with some awareness of each other. An aumbry, a small rectangular recess in the wall used to store sacred vessels, survives near the south angle, as does a latch stone and drawbar socket in the north doorway jamb, the fittings of a door long since gone.