Look closer, and you find that its basin is almost always full of water, not because of any spring or pipe, but simply because whoever shaped it never cut a drain hole. That omission, deliberate or otherwise, has kept the stone perpetually wet for centuries, and in doing so has preserved a belief that the water pooling inside it carries the power to cure headaches.

The trough sits immediately east of St Finden's Cross at Aghowle, a site associated with St Fintan of Clonenagh, also known as Fenden or Finden in local tradition. The granite block is substantial, measuring 1.3 metres long and 0.43 metres high in its current state, though it is thought to have originally stood considerably taller. Only one side has been worked into a flat face, and the rim along that side sits noticeably lower than the rest, suggesting it was shaped to allow access to the basin within. That basin is trough-like in form, with straight upper sides that slope gradually inward toward a narrow base, giving a V-shaped profile when viewed across the short axis. It measures 0.84 metres in length and reaches a depth of 0.55 metres. The nineteenth-century scholar John O'Donovan recorded the local understanding of the water it holds: that the stone itself retains the blessing of St Fenden, and imparts that blessing to every drop of rain that falls into it, making the collected water efficacious against headaches and similar ailments. It is the kind of belief that attaches itself to particular objects rather than general places, and the specificity of the stone's shape, its perpetual water, and its proximity to the cross all seem to have worked together to sustain it.