Please Help me ID this?

[tworeeftanks]

This is growing on one of my rocks in my 180 display. It appears to be challenging my keds reds although not really harming the keds. It seems to be growing from a translucent spongy like base in the rock. There are some small feather dusters growing around it but it they are not feather dusters themselves. They white extensions are brittle to the touch and break off easily.

 

[tworeeftanks]

More pics pls help identify

I think this is of the sponge family...these rocks were in brute bins for several months in the dark so my thinking is the sponges grew. The interesting thing is the stringy things coming out of the sponge appear to be photosynthetic. For now the rock has been yanked from my tank. Any one have any idea what this could be?

 

[tworeeftanks]

another pic

whatever it is its not harming my keds reds...