This star is a omnivore and is likely to eat a lot of things - even possibly your hermits, definitely snails, corals, anemones, scallops, clams, etc...and even possibly other seastars like it.
It must be kept regularly spot fed but this may not prevent it eating other things.
Water parameters for any star is critical, especially specific gravity, which should be no lower than 1.024 at a minimum.
IMO, not the best "scavenger" overall for a clean up crew at least.