copepod culture - 2 odd critters? rotifer and ??

[errand]

I have a 2L copepod culture in a coke bottle going at the moment, part of my plan to attack a dino infested frag tank [its working]. 

I can see the larger guys in the bottle easily, but I have been taking a sample and looking with my microscope out of curiosity. This is a wild zooplankton mix [Australian] so there are literally tons of strange things in there. I think what I'm seeing is rotifers in the first picture, but have literally zero idea on the second picture, I'm floored. I don't even know how to start describing this guy. It looks like a cartoon character. I moves with a little 'arm' sticking out between two giant eyes or balls. And it kind of slowly barrels around. They are under 100x magnification so they're not really that small, not like the phytoplankton that i can only get a similar picture with at around 600x.

 

Does anyone know??

[jambon]

Maybe a stray larvae of some crustacean?

[errand]

You might be right about that! Its really hard to describe these baby animals, the more I google the more I realise there is still a LOT to learn about them. 

[DISQUALIFIED-QQ]

kinda reminds me of a sea louse, interesting.

[Tired]

I don't know that it's possible to ID the little thing with eyes for sure. Crustacean, I'm sure, but that's not exactly a small field. I would probably not introduce it into your aquarium- it's probably harmless, but who knows.