I have a small blue star that came in on one of my rocks{I love free stuff}a juvinile blue usually will be light blue with dark grey splotches an adult will be a royal blue it is the only reef safe starfish{in my opinion}there is. It is light sensitive and will retreat during the day.It is also a scavenger and will mostly take care of itself,i have taken a small piece of fresh shrimp on a bamboo scewer and stuck in the substrate close to where it is hiding and it will eat this.It seems a good way to feed it because you can remove the uneaten portion easily. It is asexual and will also mate with another blue star. it can creatate another star by droping off one of its legs this is very common of all stars check out your encarta encyclopedia.Very good info.Also that fish will move faster than you might think.