I spotted this during an afternoon of shooting in New Lanark and the Falls of Clyde nature reserve with Antonio Marques back in July. The structure on which the moss was growing was one of the two 6 foot diameter water pipes leading from the dam above Bonnington Linn waterfall to the Bonnington Power Station at the bottom of the hill. The contrast between the organic, fractal shape of the moss growth against the very regular, seam line and rivets was rather appealing.
For the technically inclined...