What are these on my glass? Good or bad?

[gabrielcj]

Hey everyone!
I set up this 3 gallon pico 2 months ago and I just beat some dinos with a uv filter. Now I am noticing these little critters on my glass, they have a little circular body with some very tiny short hairs coming out of it. Any idea what they are? Good or bad?

 

[dwest]

Possible hydroids. I’ve seen them in my tank at times but never caused a problem.

 

[gabrielcj]

Possible hydroids. I’ve seen them in my tank at times but never caused a problem.

Thank you! I looked it up and they definitely look like hydroids. Was able to take a better picture too!

 

[RichReef]

They usually show up on new systems in high numbers but fade out. Some will stay and get a little larger but they are not a big deal.