I noticed this before in an extract brew. When the beer is cooled and put into the FV there is a LOT of stringy clouds of particulate matter swirling around like ghostly figures moving in the beer.
In a matter of hours it settles out looking like fluffy wool, like that wadding stuff you used to get with brass polish.
When fermentation starts, chunks of it again lift off, float for a bit and fall back in.
My 'attempted' lager brewed Friday had huge amounts of this stuff, looking at the clear demi johns in the fridge during final cooling was like looking at something from a horror movie. I know we have all seen faces and animals in the clouds, but this was fairly extreme.... and I wasn't "on" anything
I'm assuming this is normal, I'm assuming it is just bits of grain husk, hop flowers or maybe even crystalising sugars and malts. I am also assuming that it floats back up as the yeast caught within it as it settles start to ferment, produce C02 that is trapped and causes chunks to rise.
The last time I noticed a lot of this was another extract ale, which ended up with a good 2 inches of stuff in the bottom (a non clear but tranlucent bucket), it moved on in a few days of fermentation and I ended up with the normal 1/2 inch.