Yellow cucumber?

[Calappidae]

Are these guys toxic by any chance?

http://www.liveaquaria.com/product/prod_display.cfm?c=497+502+715&pcatid=715

I was thinking about getting one for my 10 gallon mini reef but I don't want to lose stuff if it so happens to perish in the tank like most cucumbers are well known for..

 

[Cryophilous]

I definitely wouldn't trust it in a 10 gallon. They are poisonous and if it dies, it could easily crash a 10g tank.