ID help

[Jeu17]

Recently picked up an established tank and just noticed these things on the glass after a week of being set up. Any ID and recommendations on removal if needed?

 

[Yallnotfwme223]

Hydroids ( not harmful ) I had them in my tank a while back they go away after a while!

 

[Jeu17]

Hydroids ( not harmful ) I had them in my tank a while back they go away after a while!

That's kind of what I was thinking, but I didn't know if they were harmful. Thank you