First off, I don't know that much about sea stars but I think you're never supposed to take them out of water, that's death for them.
I don't see how it would eat frozen baby brine shrimp, look up their diet and see how you can feed it better.
My tanks (so far
5.5 gallon Planted Dwarf Puffer tank (2 Dwarf Puffers and a lot of RCS!)
16 Gallon Planted
(GBR pair, 3 amano shrimp and a whole bunch of snails!)