Green bubble algae

[emerald crab]

Yes I did. They eat them, but they rip them open and spread the spores. Foxface rabitfish eats them, but not in quantities. In other words they don't make a dent in population. Tuxedo urchins won't touch them as long as you have coraline algae in your tank.
They need very little light and very little nutrients: nitrates not detectable, phosphates 0 (hanna colorimeter).