Need help with an id

[bert236]

Have seen maybe ten of the bigger ones in the pictures over the last few days but it seems like there is dozens more almost microscopic ones just in the small amount of water I took out with the big ones. Hydroids possibly? They are swimming around if that makes any difference.

 

[maleks.reef]

Im pretty sure these are pest jellyfish, I forgot their name. I'm sure someone else can point the name out.
Edit: +1 on hyoids

 

[bert236]

Im pretty sure these are pest jellyfish, I forgot their name. I'm sure someone else can point the name out.
Edit: +1 on hyoids

I was thinking hydroid Medusa or something like that but just wanted a confirmation