The live ocean rock would sustain some other star species as long as the biofilm was there to feed it...if your tank is big enough the biofilm will have time to regrow and replenish the stars food source... personally I'm designing an experiment in an effort to formulate an alternative food source for starfish species such as Fromias and Linckias which if successful would enable hobbyists to keep stars in smaller tanks. There's been a lot of research I've put into studying starfish and biofilm biology and I'm hoping it will pay off with at least partial success in my experiment I'm about to begin.Honestly, no I haven't ... yet.
I am the type of person that tried to do all the studying & research that I can before I jump into things. And although I love the look of starfish, I could never bring myself to buying one, knowing that I wouldn't be able to keep it alive.
The ones I have now, we're all hitchhikers, so it wasn't as bad. Amazing enough, all of the tunicates, feather dusters, barnacles and things that were 'supposed' to die off, is still alive, so something has to be keeping it all alive. Maybe the actual 'live' ocean rock may hold some kind of key in keeping them alive.
I have been keeping an eye on these threads with the hopes of catching some information that would help me succeed in keeping one of the other stars happy & healthy.