A crannog is an artificial or partially artificial island, typically constructed in a lake or wetland during the early medieval period, used as a dwelling or place of refuge. The label suggests some local awareness of such a structure, yet when the area was inspected in 2000, no physical evidence of a crannog could be found.

The most likely source for the OS cartographers marking this spot is a passage in W.G. Wood-Martin's 1886 work, which describes a timber, possibly with a sharpened end, lying on its side in deep water at this location. A sharpened timber is the kind of detail that can suggest deliberate construction, the sort of upright post used to anchor the brushwood and stone of a crannog platform, but a single waterlogged piece of wood is thin ground for a firm conclusion. Whether the timber still lies there, has shifted, or has simply decomposed in the intervening century or more, is not known. The 2000 inspection found nothing to confirm what Wood-Martin saw, or thought he saw, and the origin of the OS designation remains unresolved.