Tentatively discovered by @tarkovsky with his phone and a borrowed head torch whilst on a run with a mutual friend who lives near by. After talk of alien growths we went back together for a proper look. This is actually a 200m culverted section of Meersbrook a little further upstream from the 'Stoopatron' and it features some excellent formations on a scale I haven't encountered before. This stuff had an ochre tint suggestive of iron in the water and the possibility of old mine works in the area. You'd expect the calcifications to be hard looking at the pictures but we both came out looking like David Dickinson.