Nope, that's not it either, heh. I already asked chocolateblnt.. this was his response..
"The red knob sea star is NOT the same although they are very much similar by looks. The big difference is my spiny sea star will not become a coral eater and the red knob sea star will. I think their diet has to do with location, the Black Red Knob comes from South America and the White Red Knob comes from Africa/Indian Ocean, the Spiny Sea Star comes from Indonesia."