creature id

Just saw these tubes and trails on my rock and sand. Then I saw this worm in the sand WHICH HAD SAND GRAINS GOING THROUGH ITS BODY. Do I need to be worried?

I bought a new gorg and then saw this but it looks exactly like the white polyps on my red gorg. Finally, saw it in a different location and is definitely some kind of worm or nudibranch. I don’t see damage on gorg but the polyps aren’t out all the time either which worries me. But maybe this...

Hey guys, I was wondering what these little guys are. We turned on the blue light to 50% to just look at corals for a sec and then my mom saw translucent little creatures on the rocks. I thought they were just copepods or some sort of pod but double checking with y’all. I took a video but it...

It's been growing on one of my rocks and on my crushed coral substrate. It looks like bubble algae although I'm not 100% sure it is. If anyone can ID this it would be appreciated.

Is this a fancy worm or a brittle star? I see something that looks like tube feet, so maybe a star? I do not know where i got it from, i saw no stars in chaeto, this piece of rock(the only live rock i bought) or on the small rock with zoas that was gifted to me. Will it divide into more specimens?

Here are the best pics I was able to get. He’s just going around the side glass which has a lot of film algae on it cause I mostly just clean the front. He doesn’t seem to be eating it tho as I watch him. Not once has he truly stopped moving and again I haven’t seen him actually eat the algae...