It wont be remove by just vacuum it.. I have it brushed it moderately for it to come off.Hydra. Harmless. Keep up ur water changes and keep the water pristine. Remove any extra food. When u suction vac it'll be removed.
This is an animal right?
http://www.futuretimeline.net/blog/images/216.jpg
How do they just spring up out of nowhere??
They actually seem really awesome haha. I wouldn't mind having them in my tankYes freshwater version of sea anemone. They may be introduced in aquarium on plants.
May have come in with new plants or so.
Maybe you brought some in a while ago and didn't notice.
Bettas and gourami will eat them.
Nothing to worry about, unless you have fry in your tank. They may harm tiny fish.