well, strange in general, yes, but not strange for a starfish. haven't you been to the LFS
lately and looked in the starfish tank? every so often (more frequently than i'd like to see) you'll see them disintegrating.
i would suggest a black or red serpent star. they are quite hardy and will take food from your hands. all others reef safe stars are extremely difficult to keep alive.
btw, don't go for the green brittles though..they are fish eaters.