Can anybody identify this hitchhiker sea star?

[Myka]

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.