They say that Emerald crabs will at them but I would think that as soon as the crab pops the bubble, the spores will be released. I've only ever had one bubble algae. I did a water change and knocked the bubble loose and sucked it out with the syphon. I did this so in case the bubble did pop, the spores would get sucked out. I then poped the bubble and it is filled with liquid, it is not solid.