That one piece of bubble algae (Valonia sp.) may look harmless and under control, but like most invasive aquarium plants and algae, it can quickly spread to other parts of the aquarium. The bubble algae, as its name suggests, is a bright green water filled ball of algae. It attached to substrate with an anchor point, often growing other bubbles in the immediate vicinity. Usually, aquarium keepers just try to pup these bubbles in order to get them to go away, but this never works out well. The bubbles have to be manually removed, with extra precautions taken not to pop the bubble and releasing its contents. Most people speculate that the inside part of the Valonia algae is full of spores, but others suggest it’s just water that maybe has high nitrogen content.