I agree on the Nardoa guess. That would be my guess as well.

The thing with the quick death (even in perfect tanks and with perfect acclimation) I believe is often related to them already having started the unraveling process by the time we purchase them so those usually die within a few days/weeks.

From what I've been reading it takes starfish quite a long time to starve to death so you can have one easy for half a year or more before it's gone without noticing that it's declining.

New growth however is a different thing! I would think that that definitely indicates that it is in fact doing well. You should post your secret, Kristy