The Guilding's Sea Star is a Linckia species (Linckia guilding) we occasionally get. They aren't terribly common, but we get a few a year. Ours tend to be a purplish color, sometimes with a mottled pattern. Similar care to most starfish and other Linkia species. They are a more sensitive during acclimation, so you'll want to drip acclimate for a couple of hours before adding to your tank.
Linckia (Guilding's Sea Star)