The store I work for have avoided selling those starfish because they always ended up dying before being sold. Not very cost effective on the business end and not very nice to the starfish on the personal end. Something else that may not be well known and I'm not sure if it would apply to the blues, but I have seen purples eat soft coral. I had a small one that was lifted off a tree coral and there was a huge chunk taken out of the coral right where its mouth was. These things for as far as I know have always been said to be reef safe. Seeing that, I wonder and the tank it was in was very pristine and lots of good natural growth and well matured. Have you ever heard of this before???
The carnations are much easier than the star. Use a small suringe or small turkey baster to target feed the carnations. They like lower light. They are a deep reef coral and non photosynthetic. This is why they need more phytoplankton. Mix some marine snow and cylops in the brew and have water flowing almost directly on them. If you don't already know...when feeding, it's best to do at dawn and dusk periods or when lights are off and deactivate the skimmer for a little while. Keep good watch on nitrates. Feed the tank as you normally do, but add the special mix on the off days the rest of the tank doesn't get phytoplankton. So far that seems to help keep them in good shape without overloading the system with nitrate.
We, as a people, know so much more about outer space than we do about our own oceans. This lack of knowledge can very well spell the dangers that lay in wait for us.
The oceans surely would swallow us before a rock comes down to smite the planet of it's life.