Need help identifying this, please.

[Isabel]

I found something stuck to the glass of my tank that looks like a little white dot with a slightly darker center and a bunch of little arms sticking out. At first I thought it was debris but it has gotten bigger and its many legs are constantly twitching but it doesn't seem to be moving from that spot. Couldn't get a good pic since my camera kept on trying to focus on the rock inside the tank.
Any help identifying this will be appreciated. Thanks!

 

[Isabel]

OK, took some pics and as you can see, there are several of these things on the glass. Hopefully someone here can help me identify these things and tell me if I should get rid of them or let them be. If you look at them from the side (profile) you can see that they are bumps on the glass with spines. I was thinking juvenile urchins but this many?

Any help will be gratefully appreciated!

 

[lorawalters13]

Looks like hydroids to me. As far as I know they are harmless unless you are keeping dwarf seahorses. = )

 

[Isabel]

Thanks for the ID, Lora! I was hoping they were harmless and since all I have is a FOWLR set-up, I will just sit back and relax.

 

[SleepyJ]

They'll be gone before you know it. I had tons when my tank was around the same age as yours. They disappeared shortly after.