Known locally as St Crispin's Cell, the structure is compact, roughly seven metres long and five and a half metres wide, with walls still standing to eaves height, built from rubble and granite with quartzitic quoins at the corners. Inside, a shallow wall recess called an aumbry, used in medieval churches to store liturgical vessels, survives in the south wall. A round-headed doorway connects the western porch to the nave. But the fabric tells a complicated story: the cut granite jambs, arches, and threshold stones, along with the use of tufa in the east window, point to an eighteenth-century reconstruction rather than an original medieval building. Projecting plinth stones at the north-west angle suggest that an older church lay partially beneath and to the north-west of the present one.

The site has accumulated a layered and somewhat troubling history. In the early seventeenth century, the associated graveyard was cleared, the disinterred bodies and their gravestones buried elsewhere. By 1827, a ninety-seven-year-old local man could still recall the cell as unroofed and ivy-covered, noting that the ground around it did not appear to have served as a cemetery, though the body of a drowned seaman washed ashore near the nearby Rathdown Castle had been interred there. When Ordnance Survey officers came through in 1838, local memory of the original church had faded entirely; what people did recall was that the bones from the graveyard had been dug up and buried in a single pit to the east, the work, as the account puts it, of "some bad man." The surveyors themselves were uncertain what to make of the cell, noting its whitewashed plaster interior and observing that it looked less like an ancient foundation than a small chapel of ease assembled from the stones of something older. Geophysical surveys in 1993 and 2016 added further complexity, with the later work by Leigh Surveys identifying possible rectilinear ditched features and what may be an outer enclosure to the north, though the interpretation remains speculative. Grass-covered mounds, four to five metres wide, still surround the church on three sides, and may contain stonework from a structure that has otherwise left no trace above ground.