I am not a real knowledgable fellow regarding seastars, all I could comment is that your one (Pentagonaster duebeni) was/is probably feeding on the coral polyps. Most seastars are predators or scavengers, so I think it is quite possible that this little red beast got the better of the coral.
Australian Divemaster Academy PADI and SSI-accredited - participants can enter the program with little or no diving experience and in just ten weeks hold an internationally recognized divemaster certification.
Simplicity and a user friendliness for the new & hobbyist underwater (UW) photographer is how the Sealife DC1200 camera and housing is designed. With it's UW-purpose built functions and menus, taking photos with or without UW strobes is setup to be just a few clicks away. In particular, there are unique UW functions that are not commonly found in any of the name brand cameras that will take the plunge with you on your dive trips turning UW photography into simple snaps.