Green Angel-Hair

[Pysgodyn]

Hiya guys, as always I wonder if you can help me identify and explain (or post a link) a bit more about what I don't know about (!)
I have (for many months now) had a green angel-hair like plant/organism/algae(?) in my tank. It started being attached to one of the plants, but now it's 'growing' very quickly and doesn't really care what it attaches itself to (even the only fake plant I have). The only way I can describe it is as the old fashioned Christmas decoration called "angel hair", but green.

• What is this?
• Is it harmful?
• How, other than pull at it, can I get rid of it, or prevent it from growing?

Thanks, as always.

 

[nosoup4you]

Sounds like what you have there is green hair algae. Have a look here and see which looks most like what you have.