Missing Urchin

[SMSHAPERO]

I had a long spine urchin in my 40-gallon tank for 3 years. Suddenly he disappeared. I found no shell and there are no spines anywhere. He didn't fall out as there is a lot of open space around the aquarium. What could have happened to him? The only other critters in my tank are corals, a damselfish, and a Halloween crab. I haven't added anything in over a year. Wierd!

 

[MnFish1]

I had a long spine urchin in my 40-gallon tank for 3 years. Suddenly he disappeared. I found no shell and there are no spines anywhere. He didn't fall out as there is a lot of open space around the aquarium. What could have happened to him? The only other critters in my tank are corals, a damselfish, and a Halloween crab. I haven't added anything in over a year. Wierd!

I had one go out of the tank - and literally crawl across the floor. My guess is that this is not what happened - but - ??