Can anybody identify this hitchhiker sea star?
 

I found this hitcher on a rock I got recently. It is about the size of a loonie including the tentacles. Anybody know what it is? Good, bad, reef safe, keepable? It is somewhere in my sump at the moment.

The size of a loonie? Hmmm, likely too big to be an Asterina sp. Most starfish are predatory, often only stripping your sand of all life (which isn't good, and the number one reason I'm not a fan of "sand sifting" stars), but personally I wouldn't risk it. The only starfish allowed in my tank are Asterinas, Mini Brittle stars, and Black Brittle stars. The first two which are hitchhikers.

I tend to agree with you Myka, unless I can find information that tells me this guy is safe, it will probably go away.

I am not 100% sure but the color formation reminds me the Sand Sifting Sea Star
If you have LV this is a good sanitary
Take a look:

http://liveaquaria.com/product/prod_...572&pcatid=572

I don't think it is a sand sifting star like those ones, but who knows? Nothing I have seen yet on the net matches it perfectly. I will try and get a better picture of it when I can. Right now it has gone missing in my sump. Probably busy eating all the fauna in the sand or dying somewhere...