HCA: Hermit Crab Association

I noticed yesterday that the screen ontop of the exo Terra is starting to rust. Has anyone had this issue? If yes, how should I handle it? I am pretty surprised because I have only had issues with rust if I cut open thr screen and plus exo Terra's can be used for tropical environments. My other question is, are those expanding clay balls hermit safe? It says they are for humidity and I think a lot of people use them for a false bottom? I don't think I could add them to my enclosure because the five in there are already too big for it. (They are staying with me temporarily as rescues)
Thank you everyone!

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Remember, the rust is due to the salt... Normally these things don't have salt in the tank. Those expanding clay balls are great for froggers and other herp keepers where their animals will not dig. Not to mention, those clay balls and turn into mush (I assume every few years) so you will have to "restart" the tank, adding new clay balls to keep the "false bottom" in working order.

Thank you AuzzyJJDude! I didn't even think about having to restart. For some reason I didn't consider them turning to mush lolz. I guess best not to trust the hermits due to their digging.