What do you think this is?

[toomanymatts]

I have it on three clusters on the back of my tank.

 

[vetteguy53081]

I have it on three clusters on the back of my tank.

Appears to be yellow sponge

 

[toomanymatts]

Keep or kill?

 

[ISpeakForTheSeas]

Personally, unless it starts overgrowing other things in the tank/getting out of hand size wise, I’d say keep - but that’s just me.

 

[Sean Clark]

Keep. Super cool.

 

[toomanymatts]

I don't clean the back wall or the side black wall that house the filters. It's a free for all there. If it gets on the display side it's gone.