A couple of years ago a golf ball sized clump of white fuzz was fished out of some blanket weed on a pond dip. I had no idea what it was until I spotted the brown snorkel sticking out the water: it was the egg cocoon of the great silver water beetle!
Unfortunately it would no longer float the right way up, so I placed it in a pot in some water until a day or so later when it hatched. I moved it into deeper water in a photographic aquarium (which I hadn’t cleaned recently!) and filmed it. I’m not sure this has ever been filmed before so it was rather exciting. Here it is….