It is not a myth at all, these algae do contain "spores" but if you want to use these for propagation, you have to pop the bubble when it is "ripe"and make sure that nothing will eat these spores in your tanks after their release.
I have popped one bubble in a bucket of seawater, and several weeks later I had literaly millions of small bubbles growing on the sides and bottom of the bucket.
The best time to pop them is when they are big and have just "lost" their internal pressure. at that time the spores are "ripe" for propagation.
Most people do not like the bubble algae in their tank, but I had one reeftank in a Resort in Cairns and the few big bubble algae it had were "attracting" the attention of the Tourists more than the fish or very nice corals in that tank. These ill-informed people taught these were big "black pearls"and were absolutely fascinated by them, only a very few people with reef-tank experience knew better.
lol - if thats what they want to think. I wish I could convince myself that hair algae was something good!
I dont particularly care for the bubble algae. When I clean my tank I try to siphon out what I see. Occassionaly they pop but Im usually right on top of it with a siphon hose.
