New growth in tank. Please help.

[matthewhmaxwell]

I have a live rock tank and am just getting started with adding some corals. I noticed this new growth on one of my rocks. It looks scary. Any info out there on what it is and what I should do about it? Any help is appreciated!

 

[organism]

Looks like a sponge or some kind of harmless filter feeder, shouldn't be an issue.

 

[chefbill]

had mine since day 1 in my tank. 17 months. Looks the same as yours