Yellow sponge? Maybe?

[saitoking]

Hi all my tank is fish and live rock been setup for 18 years don't really know what this is but it looks cool. Any help would be welcome. It started out about 10 years ago and has spread to 4 other places in the tank. 2 things the yellow stuff and then towards the bottom of the picture in the hole there is something growing. It white with some blue 2 and yellow around the edges. Thanks saitoking

 

[Northstar24]

I would also say its some sort of sponge or tunicate

 

[Waddi]

+1 North.
Nothing to worry about, simple filter feeders.

 

[Bifferwine]

I would guess #1 is a tunicate, #2 is a sponge.

 

[saitoking]

That's cool something growing that's not bad hehe. I have one other thing growing that I don't know what it is. It's about 3/4 of an inch and they are growing in most darker part of the tanks. Thanks for the help. saitoking

 

[Waddi]

Pineapple sponge looks like.