invisible writing

At first, upon unearthing the coiled thing from somewhere underground on my way down to the bottom of the root of one of the big docks infesting the allotment's fruitcage, I thought it was a wee bindyweedyrooty sort of coiling plant-thing which had become disoriented. It quickly resolved itself into being a bit of string, through with less reason to be in that shape. When it dried out it lost the spiralleyness.