Can someone identify this?

[Picard's Lionfish]

I found this in my overflow. I have never saw anything like this in my tank. I have TBS live rock. Tank is almost 2 years old. I have a couple of red bristle stars that like to make their way to the overflow. I'm wondering of there has been some hanky panky going on in there. The inside has somewhat of a star shape. The shell is hollow with a quarter size hole in the base. The whole thing is about the size of a half dollar

 

[saltyfilmfolks]

That’s an urchin shell.

 

[Picard's Lionfish]

Do they molt and leave that?