This first one is probably a Spaghetti Worm (Terebellid) - harmless/beneficial if so.
This one may be a peanut, ribbon, or spoon worm, but I can't tell from the pic (though it does seem awfully long and skinny for a typical peanut worm) - if you can get closer up, clear pics (preferably under slightly brighter white light), I may be able to offer a better ID there.
This is a good pic of the underside, but we'd need pics of the top (and preferably side as well) to try and help you get an ID on this one.
Hey, the flat critter on the glass hadn’t come out until today. I managed to take this picture of the top side. I’m not sure if it’s the same one because this one looks smaller and has a more yellow/brown color to it. As for the side, it’s just flat and transparent.
If that's the top and the critter is flat (not really rounded/taller in the center), then that's a flatworm of some variety - you probably want to remove it, and flatworms are generally neutral at best in this hobby.
