Ping pong sized green algae?

[Leslie]

There has been a round, very smooth, bright green ball growing on one of my rocks for months, starting out about the size of a small pearl when first noticed. It isn't Valonia (unless Valonia can grow singly and get to be very large?), and is about the size of a ping pong ball. It isn't translucent. Depending on how the light hits it, it can look smoky black. I'm pretty sure it's algae, but I can't find an ID anywhere. Any ideas?

Thanks
Leslie

 

[Chucker]

Leslie, it is indeed Valonia. Depending on the variety, it can be large, solitary cells like you have seen in your tank, or smaller colonial types.

 

[Leslie]

Valonia? Interesting. Never knew it could get that big. Should I try to remove it? If it bursts, will I have hundreds of them? In short, should I do anything?

 

[Anonymous]

It may not even be attached to the rock it's sitting on. If you want it out, then just go ahead and take it out. I've never had a problem with valonia spreading, even when it burst in the tank. In fact, I think it looks pretty cool.

 

[Leslie]

Sorry it took so long to say thanks, but "thanks". I think I'll leave it. It's a fascinatingly beautiful ornament in the tank.