Hitchhiker ID

Hey all, i need some help...again! I just purchased some LR from my LFS and it came with some "creatures" im not too sure what they are. Maybe some of your expertise can help me. I attached the photos on here, so i hope this works. If not, ill have to find another way to show u the pics.

Pic #1) I think it is a brittle starfish, but im not sure. If it is, will it grow to be any bigger b/c i have about 20 that came in/on the rock

Pic #2) Possibly some sort of starfish? I have 2 so far, one with all its arms and one with 3 full arms and what looks like 3 or 4 stubs. Their color is kinda greyish brown with redish marks on it

Pic #3) Have no clue about this one, except that it has a clearish white bubble like bottom and it moves very slowly

Pic #4) theres quite a few of these things, they have the same clearish white bubble like bottom and they move very slowly, they are also a neon green color when the actinics or moon lights are on. i have tons of these on the rocks

Pic #5) this might be another type of starfish, its white unlike the ones in pic #2, with a redish pink dot in the center of it.

All these hitchhikers are very small...mostly a little bit bigger than the size of a pencil eraser. Please help if you can!! Im curious to know if any of these things will cause problems for me in the future.

Thanks,
BLONDIE!