What is this?

[tony_caliente]

Tank was initially set-up as a FO tank over a year ago. Converted to a reef tank 3 months ago. Perfect parameters. Looks like whitle, thread-like, cilia. It's only attached to the back of my tank glass. Just noticed it today. Does it need to be removed and how?

 

[tony_caliente]

Thank you. I own both.