Urchin help needed
 

My urchin was fine yesterday and this morning he/it is on it side and not moving very much. I can still see it's mouth/beak moving. Any ideas on why it would change over that fast?

How long have you had it?
What have you done that might change water conditions?
What are you feeding it? Try dropping some nori on it to see if it is feeding.

Nothing in the tank has changed. No movement all day. Do they go into hibernation or anything like that for molting or anyhting..........