If it's truly a feather star and not a basket star you should be feeding much smaller food particles. They usually don't ship well and need tlc to recover. Try cyclopeeze, baby brine shrimp, Rotifers, nutramar ova, fauna Marin ultra min F, fauna Marin zoa food, coral captive E... Try stirring up your sand bed and dosing phytoplankton. Check out the fauna Marin forum and non photosynthetic forum.