The outcrop itself carries a name that signals something older and stranger than Christian piety: Cloch-an-Phuca, the Puca's Rock, anglicised to Clopook. The puca, in Irish folk tradition, is a shapeshifting spirit, neither fully malevolent nor benign, and the fact that this particular rock earned its name from one suggests the place was long regarded as somewhere slightly outside the ordinary. The cave mouth, wide enough at 6.6 metres across to feel more like a gash in the cliff than a conventional cave entrance, faces south-west and opens into an irregular chamber roughly 11.5 metres deep and up to 5.2 metres wide, its clay floor giving way at the far end to a narrow passage running north-east for an undetermined distance.

Daniel Byrne, writing in 1852, placed the site about two miles south of Timahoe in what was then the Queen's County, and suggested the hillfort above was probably one of the chief fortresses of the O'Moores, possibly even a royal residence. He noted that by his time the back of the cave had been closed off with dry stones to prevent cattle from wandering in and becoming lost, a practical measure that inadvertently preserved the tradition of a deeper interior. That tradition has an older and more specific layer to it. The Vita Tripartita of St Patrick, attributed to St Evin, records that St Fiacc, Bishop of Sletty, a monastery located some seven miles to the south-east, would retire on Shrove Tuesday to a cave on a hill called Drum-Coblai, taking five barley loaves mixed with ashes. He remained there through Lent, returning to Sletty in time for Easter, bringing a portion of one loaf back with him. A later scholar, writing in the Loca Patriciana, identified the Clopook cave as that same penitential retreat. Comerford, recording local tradition in 1886, added a further detail: people in the area still spoke of a saint who fasted and prayed here, and who returned to his distant church afterwards by way of a subterranean passage running south.

The cave remains accessible today by a pathway that climbs the western side of the hill to the opening. The chamber's clay floor is deep enough that badgers have established extensive setts in the north-western corner, some seven metres inside the entrance, and the narrow channel at the far north-eastern end of the cave, whether formed by animals or by something older, continues into the rock for an unknown distance. The question of whether that passage connects to anything further has not been resolved.