Hydroid, Spider, other?

[stAlphonzo]

At first I thought these might be some zoanthid eating spider since I have a zoanthid and it totally closed up yesterday and is looking sad now. I did read some id posts though that lead me to believe they might be Hydroid Jellyfish though so I figured I should confirm so I know what to do about it. My tank is almost 2 month old and they showed up yesterday, possibly on some snails I added.

Here is the view of its underside while on the glass.

Here is a side view that shows it has a little center protuberance. It almost looks like a mini octopus when it swims. It's pretty cool provided it isn't going to destroy my tank ;Nailbiting

Thoughts, advice, condolences?

 

[saltyfilmfolks]

Hydroid. Medusal stage of a hydroid actually.

Jellyfish and hydroids use a similar breeding style sonit swims like a jelly.

 

[stAlphonzo]

Thanks salty, that's a relief I think. I read that there really isn't anything to do but let them die out, right?

If that's so, I guess my zoanthid's anger is just a coincidence.