Jellyfish hitchhiker?

[Ishai Thatcher]

Hey y’all, I got these in a tank that had nothing but a peacock mantis and a sponge filter. Looks like a jelly to me, I got a lot of them. They sit on glass as pictured sometimes but if disturbed will jump off the glass and start free swimming. They also swim around naturally during the day. Any ideas?

 

[HeyLookItsCaps]

They’re called hydroids, unusual little critters, had them show up in my old biocube!

 

[Ishai Thatcher]

They’re called hydroids, unusual little critters, had them show up in my old biocube!

Thank you! Super fun to watch and there is nothing in there for them to bother!