Pincushion sea urchin dead?

[JennyH3]

My pincushion sea urchin has been going strong for a month. Carrying hats moving all over the tank.

today I found him upside down. His feeler things are still there.

He won’t stick to the glass.

see video - https://youtube.com/shorts/slbrkj58fYE?feature=share

 

[blaxsun]

If it's not losing spines it's probably still ok. They don't always like being on the glass. You could offer it a small piece of seaweed wrapped on a rock?