What's this growing on LR?

[Dark knight]

 

[Jaffy]

Sponges buddy! A sign of good water so far, harmless, stay small. Filter feeders, don't do much of anything. Some grow larger then others.

 

[Dark knight]

So all normal then lol have seen 1 or 2 on the glass too

 

[Dmorty217]

They are called pineapple sponge, caused from excess silica in the sand/tank they should appear everywhere until the silica level lowers then you will see only a few

 

[Joe]

Looks like small tunicates to me....... Harmless.

http://www.reefcentral.com/forums/showthread.php?t=1890929