[Delphinus]

They eye thing is actually his butt. In and of itself, it being deflated is not a sign of trouble, it comes and goes.

Pale needles is weird, I didn't think they changed colour so much, not sure what that can mean. If it is really stressed it will drop needles but if it recovers they will regrow. If it dies you'll know because all the needles will be off and the shell part will be mostly empty anyhow by the time you notice that.

Urchins are pretty sensitive to changes though and generally require a gentle and slow acclimation so it's a good bet he is in recovery mode from being dropped in. However there's not really much you can do at this point except leave him be and hope for the best. It could take a couple of days before he's running around.

I'm sure he'll be OK. Good luck!