Something growing and What's that? ID please!

[Yuki Rihwa]

So there something growing on my Xenia rock and 1 on my clam shell, notice coraline growing on my clam shell too and this weird thing just join in from nowhere LOL picture below:

a lot more on Xenia rock, I have this Xenia for months so it's not new in my tank.

Can anyone ID them? good or bad? of course I hoping it's a good stuff since it doesn't bother my clam at all. Thanks in advance.

 

[ewelch]

Sponges

 

[ewelch]

Sponges

 

[ewelch]

Sponges , good stuff

 

[needbiggertanks]

Yep. Sponge

 

[kazikage42]

Pineapple sponge. Very beneficial to the tank

 

[Yuki Rihwa]

Thanks all, now I can sleep peacefully or I will waking up and using flash light to check up my tank