I was given a blue starfish from my boyfriend as part of my Christmas present. I think it's a linckia laevigata, but I'm not 100% sure. I was real nervous b/c I know they're hard to keep and my boyfriend just meant well. I acclimated him for 2 and a half hours, drip method. He seemed to be doing great. Hiding during the day coming out at night. I just came home from being away for the night and found a leg detached, but still moving. Looks like there is a whitish/cotton spot. Now I know this probably isn't a good sign...my quesiton is, should I take him out of the tank and setup his own quarantine or let him be and see if he regrows his leg? Help 
I'm going to feel horrible if this poor thing dies!
I'm going to feel horrible if this poor thing dies!