Help identifying bubble-like things.

[kickin]

I noticed these bubble-like things growing on my liverock and dont know what they are.
I have a 125g that has been up for about 7 months.

 

[itchy]

It looks like bubble algea!

 

[stuckinfla]

Dont just pop them either, they will spread!

 

[jjlittle]

I have always heard them called sea grapes they will spead just pick them off they are not bad as far as i know my friends tank has hundreds he just tries not to pop them when plucking them out.