That doesn't sound like bubble algae. The bubbles don't have "dividers." There is a species of bubble algae that is cigar shaped, but again, it has no dividers.

I did find the possible species name for the original post. Valonia aegagropila. Sometimes its hard to ID these things from a pic. Sometimes you have to look at it under a scope to see how they are arranged.

http://www.botany.hawaii.edu/reefalg...egagropila.htm