I had a star do the same thing. It will eventually just become the center with no legs. I agree with moving it to another tank though, just in case.
I've found most starfish to be very very fragile and not do well in the home aquarium. They do not do very well in newer tanks especially. :-(
The only hardy star i have ever had is the sea serpent ones, they come in several colors too so you might consider that if you want to replace this one.
180g- Mostly BIG fish and some coral. ~80g Nuvo- My coral tank with "happy fish"~ 90g- FOWLR Not the not happy type of fish~ 125g- Freshwater Malawi Cichlids ~10g- Nuvo- The refugees from the Ich of '18