Flis

Similar absorption in the duck weed covered pond in the back garden would have made a better snap: bottom up, head down, arm stretched down into the weed infested water - but the telephone was not to hand at that point. And even if it was, my appointed task was to collect the weed being fished out of the pond, not to mess about with my toys.

Next problem: do ducks actually like to eat the stuff? I believe that it is full of all kinds of interesting nutrients - which means that there is little left for anything else in the well-shaded water below.