has your starfish been looking despondant lately? have you checked his wrists for self inflicted wounds? How about getting a phyche consult? Depression can be treated- there are a lot of good meds out there.
I have some more helpful ideas, so read on
I am just guessing here, but maybe the starfish wrapped himself around the heater when it was off, and not being a warm blooded animal (i am assuming theye are not warm blooded), when the haeter turned on, if it was a gradual enough temperature change, he may not have realized the temperature was rising. In biology lab, we did this experiment where we put a frog into hot (not boiling) water, and he jumped right out. we took the same frog (we had a sick biology teacher, ok?) put him in cold water on a burner, and SLOWLY increased the haet over the class period till it was boiling. the frog never noticed the temparature change, and was boiled to death. Maybe this is what happened to the starfish?