DEFINITELY not just a sand sifter...beware!!
Especially the behavior...sand sifter stars do not tend to eat any flake food, etc.
This star, according to the most excellent book "Sea Stars, Sea Urchins and Allies: Echinoderms of Florida and the Bahamas" by several echinoderm scientists eats:
Wells et al. (1961) characterized it as a voracious, nonselective predator. By examining the gut contents of 124 individuals....they identified 91 species of invertebrate prey. The predominant items were gastropod, scaphopod and bivalve mollusks, other prey included small crustaceans, juvenile sand dollars and juvenile A. articulatus...feeds on callico scallops
I left out some parts just to give an idea of diet.
Should be considered a predatory star, IMO. Not reef safe. Not a basic sand sifter.