What is this

[Bulldog5]

Got this stuff growing on a rock and it's getting bigger anyone know what it is? If so is it bad do I need to get rid of it? It's yellow and looks like balls of string and I think I see some tubes. Sorry for bad iPad pic I'll try to take better one with phone later. But it seems like it spreading

 

[Bulldog5]

Better pic

 

[b.lebeux]

Looks like a sponge, the pic is blurry though... post another picture with the focus centered on the actual sponge if that's what it is.

 

[Clink51]

i second sponge

 

[crox99]

Yep sponges. They are good to have.

 

[Bulldog5]

Thank u very much I'll try to get a better pic tonight

 

[Jazeel55]

They usually die after awhile.

 

[gpscuba]

I had a yellow one for a while it is no more . Now I got a purple one growing on my rock

 

[rookie07]

I agree with above, sponge. If your tank is mature it'll do well. Sponges die in bad tanks and thrive in good tanks.

 

[gpscuba]

I have them growing in my new 55 gallon they are bright yellow with the little tent of green started to see them in a few areas I agree they look to me to be sponges

 

[Ryanr1212]

Sponges are cool and add to the biodiversity of the tank. I would keep in IMO