I bought 2 thinking they were "common" stars. One never really acted right, it died after a month by losing its legs and then expelling its guts. The other one seemed hardier until he happened to be right in front of the return while I was screwing with the pump and got a face full of microbubbles. The next morning all his skin had fallen off. Both deaths were grim. I wouldn't do it again.
I couldn't get them to eat anything, the healthier one liked to chill by the surface with its feelers in high flow. Maybe it was skimming food that way, or eating biofilm that it got off the glass. My tank was over a year old at the time.
Maybe look at an urchin instead? They are neat critters, come in lots of colors. I think the only thing they mind is high nitrates. They'll eat coraline though so that might be an issue if you like to have a lot of it.