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.