OK Guy. I didn't say it was the biggest I've ever seen :?
I've got some coraline encrusted mondo bubbles but they are at the bottom. Put the ruler to yours...just how big is that monster? 8O
When a bubble is mature, it is easier to pull out with the rocking method. If it doesn't rock back and forth easily, leave it alone for a month and try again. If it isn't hurting anything or bothering you (it's not an epidemic) leave it alone. Macro alge will compete with it so you should only have a few.
Mark