If left untreated it will become a pest algae. Best way to remove it is to prepare two buckets of saltwater big enough to dip the rocks in. Take the rock out, scrape the bubbles off but try not to break them. Invariably you will break some though. Either way once the algae is removed and thrown in the trash, dip the rock in bucket 1, and then bucket 2, and put back in your tank. You may require multiple treatments longterm but this is really the only way to do it. Best to do it now before the problem escalates.
Do not, I repeat, Do not, pop any bubbles in your tank. This releases spores that will just enflame the problem