Dead Sea urchin

[johnnycamp5]

Hello fellow Reefers

Any idea what would cause a violent destructive overnight death to a sea urchin?

I’ve had one urchin (white colored) in each cube tank for months now…
they’ve been doing fine

Three weeks ago I bought a smaller, medium brown colored urchin (with darker brown stripes) to put in my larger cube, which struggles more with brown hair algae

All was well until I did my water change yesterday…
I was sucking out pieces of his brown circular shell, and couldn’t understand what on earth happened!!

I’m wondering if my large emerald crab ate it overnight?

Can’t figure it out, the white urchins are both fine (one in each tank)

Only other inhabitants are some snails, a cleaner shrimp, 8 Green Chromis, 1 hippo tang, 1 six line wrasse, and a pair of ocilaris clowns

 

[Rocks reef]

I've heard of emerald crabs becoming aggressive especially in overcrowded tanks to being stressed out. I cannot say for certain that is what happened. Also, sometimes, things die for no apparent reason. The urchin may have been stressed during shipment, may have injured during shipment, who knows.
I'm sorry for your loss though!

 

[johnnycamp5]

Thanks

Picked it up from my local reef Shop.
it’s about a 20 minute commute lol

Oh well