Not enough room for all of those extra shells? Tired of digging them out of the substrate? To help maximize surface area on which the crabs can walk and still keep all of the shells in the tank, I have constructed a shell shelf (aka shellf) out of a piece of 1/4" plexi type material. I went to my local hardware store and had them cut it. I then lined the outer perimeter with tiny corks to prevent the shells from falling off. I used aquarium sealant to hold them in place on the piece of plexi. I let it set for at least 72 hours before putting it into the tank. Both to help cure the sealant and eliminate any fumes. My shellf is triangular to jazz up the tank a bit, but a square one would work just as well. I then constructed cork huts (you can see them underneath) on which the shellf sits. I didn't adhere them to the shellf because it allows me the freedom to position it wherever I'd like to accomodate different decorating schemes when rearranging the tank. If you don't like the look of the corks, you can always hide them with a little ingenuity and some fake plants. I removed them so I could show in the pictures how I went about making the shellf. Of course, it doubles as a nice little hiding spot for the crabs too. Just make sure you provide some way for the crabs to get up to the shellf and you should be good to go. If you want any pointers, pm me and I will be more than happy to help you out One more thing-the corks are nice because they don't mold! My crabs have not had any problems utilizing the shellf. They change shells all of the time and are smart enough to know where the extra shells are kept, so don't be worried that they won't find them LOL. I posted this somewhere before (probably got off topic in another thread LOL), but thought I would make a separate thread for easy reference.