Anyone know anything about sea sponge?

[Pier Pressure]

You know what is really weird? I had purple sponges grow in (lots of little pockets of them) on live rock that we had out of the water for a good hour while we drove it across Calgary. We have had it since we got our tank up and running in November.

I had a die-off of livestock that I blamed on water quality. If the sponge and corals made it - must have been a different issue?