Help Immediately Please! Urchin

[The coin]

I have a 90 gal fowlr. Mid section mound of live rock. Small caves etc. My 7 month old sea urchin, disappeared. Searched everywhere. No spines. No pieces of him
Anywhere. Like he was taken out of the tank. Help please!! Any idea?

 

[mr_X]

He will probably pop up eventually. They can get into some pretty tight crevices in search of food.

 

[The coin]

He popped up haha thanks man