UNK archaeology, back garden-to-be

UNK is the noise a spade makes when the blade hits stone. Archaeology might be what you do next. UNK is what happened this morning so, channeling our inner Prof Alice Roberts, we dug, troweled and brushed round the UNK generator. A bit of paving stone, previously cemented onto the Mystery Thing (500mm diagonally),  was scientifically and delicately removed (sledgehammer, crowbar). Nothing known about the history of the site suggests an earlier building. It's not on the line of an old boundary. It's not where the old shed was. Not where the old oil tank was. Forensic scientific analysis of the UNK source says twentieth century. Too heavy to lift. So we're burying it again.