HCA: Hermit Crab Association

I was checking up on the tank last week and found the large piece of wood in the tank had unfortunately broken out with mold. I have seen some people say it is safe but it is unsightly and could cause issues with me or the crabs in the future so I removed it. Now I am looking around to replace it and the main ones I am finding in stores are cork bark/rounds, mopani wood, spider wood, and I found a really nice peace that according to the tag was grapevine but didn't look much like it. I read that the spider wood could easily break out with mold the the high humidity and relatively dark conditions in the tank but I do spray down the tank with salt water. Additionally I read that cork bark is supposedly hydrophobic making it harder for it to grow mold. I also have some old pieces of cholla wood in my box of hermit crab supplies I could use. What kind of wood should I try to use?

If you don't like mold, boiling your wood in heavily salted (can use plain salt, you don't have to use marine salt) water, and then letting it dry before putting it in the tank will decrease the chance of mold.

Any wood can mold in high humidity, I've had untreated cork go completely green on me before. I salt boil - pound of plain cooking salt (no additives, just salt) per gallon of water. Boil for 15 minutes, in sections if needed so the entire thing gets evenly treated. Allow to completely dry before going in the tank. I never get a resurgence of mold! And it allows me to salvage otherwise nasty pieces and works on everything from cork to grapewood.