If I were a Crab I would love my reef tank for a home. I would enjoy regular meals and not have to dodge that pesky sea gull. My home has a great reef of rocks and sandy beach area. 
I would want for nothing as my owner love to take care of me and the reef tank. The lights in the tank keep me warm and I love not having to scrounge for something to eat. The food is the best as in the wild I would have to settle for rotten left overs. I even get to watch Mo Howard West Virginia Football on my owners TV .