This is bubble algae, correct?

[C.Eymann]

It's still "bubble algae" though right? Kind of like how people refer to a Sarcophtyon as a "leather coral?

Valonia sp. is what people typically call bubble algae in the hobby, I read a bit more about the genus Dictyosphaeria sp. and it can reproduce vegetatively and sexually, so good thing OP took the rock out of the tank before removing it and potentially causing it to spread more, without more experience with this algae in the hobby we wont really know if its is potentially as invasive/bad as Valonia sp.
I don't think it has a common name yet in the hobby, I guess you could call it bubble algae.
I like Cstrickland's reference to it looking like a clump of frog eggs. Frog egg algae?? egg sac algae ??? kinda of a chewy sounding but I like it.:bounce1:

 

[Egg]

I'm assuming you did read that link posted above? (Bubble Algae) I'm pretty sure they did reference this stuff in that artice. Sometimes things get lost in translation when people get all scientific and stuff. "Layman's Terms" can go much further sometimes.