Can anyone ID these critters? (Mostly starfish)

[angelap]

A friend of mine just came back from Jacksonville FL and brought me some critters back.
1. "Classic" looking starfish - Sandy bround color: I'm pretty sure these are sand sifting stars. I was going to put them in my reef tank, but after reading some post here it sounds like this is not a good idea.
2. "Linkia" looking starfish - But it is not smooth. It has a base color of black with raised peachy-orange color pointy bumps all over. The underside is peachy-orange and it is very active.
3. "Classic" looking starfish - Looks just like a sandsifter star but is purplish on top outlined w/the peachy-orange color.
4. Large conch??? > The foot is solid blackish. The shell is tan and brown. It is the typical spiral shell with the pointy end.
Let me know what you think. I don't have a camera so I can't get a pic. I would like to put one of the conchs in my tank, but not if it will kill my clam or corals. I think I'm going to take everything else to the lfs to see it they'll trade me for something.
Thanks,
Angela

 

[ophiura]

Without a camera it is very tough:
1)Perhaps Luidia clathrata if it is kinda flat like a sand sifter. A voracious predator.
2) Echinaster sentus - probably reef safe, sounds like a juvenile. No guarantees
3) Astropecten articulatus - voracious sand sifting predator, including on snails, other stars, bivalves, small crustaceans.