That uncertainty is itself the most interesting thing about them. The stones, none taller than 0.65 metres, lean noticeably out of the vertical, embedded in the peat and arranged in what appears to be an arc or shallow chamber running roughly north to south across a span of about 2.25 metres. Archaeology tends to reward the definitive, so a site that simply cannot be classified carries a particular kind of quiet weight.

The three boulders sit some 35 metres south-west of a nearby stone row, which is itself a modest prehistoric monument of aligned upright stones whose precise purpose remains debated. Lord Killanin, writing in 1954, proposed that the grouping at Derryinver might be the ruined remains of a megalithic tomb, the type of prehistoric burial structure typically formed by large upright stones capped with a roofstone. Gibbons and Higgins repeated that suggestion in 1988. A megalithic tomb reduced to three leaning fragments in a bog is not an unreasonable reading of what survives, but the remains are simply too incomplete to confirm it. The stones may have once formed part of something larger, or they may represent something else entirely. Archaeology, on this occasion, declines to offer a verdict.