Unresolved Sump Creatures

Ok couple of things I have tiny worms moving along the glass in my refugium could they be bristle worms and if so should I worry. Also today I noticed something floating around in my sump a picture would not have captured it so Im gonna try and describe it as best I can. It looked like a tiny microscopic umbrella and it swims sort of like a jelly fish and it was tan I watched it float around flapping its umbrella like top straight from the refugium through the baffle and into my return pump which means hes somewhere in my DT now can you identify and should I be worried.

 

Could be bristle worms, if so not a bad thing. There a good part of the cuc.

2nd one could be hydroids. Most die of on there own. Not a real big concern either.

 

Can you describe the worms? The jellyfish looking thing could be a jellyfish. I haven't heard of anyone having any problems with them and have heard that they don't normally last long in our tanks. However, I don't have any experience with them so will let someone with experience give you a better answer.

 

Really too small to describe it just crawls along the glass and looks like a tiny worm.