Encrusting White Growth

[Walla2GSP]

I asked about a month ago, about an encrusting growth on one of the rocks in my FOWLR, and only got a single guess. Since then, I've had an explosion of growth in both tanks, and it looks like I have two different species. The first starts out looking like the white roots of a macro, then makes a criss-cross weave of white strands that almost resembles a chrysalis in appearance and has encrusted live rocks and PVC structures in the tank, and is forming a mat on the glass towards the back of the tank that I can't reach. The second kind is a greyish white translucent sticky soft tissue that feels kinda like a mushroom coral and has encrusted a small rock and is growing on a few more in both aquariums. I tried to get some pictures, but photobucket won't let me upload, and the growth is barely discernible in the photos anyhow. Anyone have educated guesses without pictures??

 

[Timfish]

First thing that comes to mind is some kind of sponge. They are good filter feeders and some feed on the DOC in you system converting it into DIC (alklainity)