I'm just about to return my long spine urchin (today actually). I've had him for 14 months but within the last two, he has eaten all my mushrooms, two red brains, a torch, and all but one blastomusa. The things got a taste for $$$ things.
I see you live in Rochester. I'll sell him to you for $5 it you want one still.
I'm definitely not saying that this is normal. I've never heard of another one doing this.