What is this?

[Leilanni]

Hi all,

I was cleaning my tank tonight and I noticed these weird egg sack like things on the side of my live rock. What is it? :hmm2:

Thank you for your help in advance!

Lei

 

[droth335]

That is a sponge - a beneficial filter feeder.

 

[Leilanni]

Thank you so much Dave! I have been freaking out all night over those two spots.