Here's A List Of Wood You Can And Can't Use
Safe Wood
Cholla Wood (it's actually a Cholla Cactus Skeleton)
Cork Bark
Cypress (swamp variety, taxidium species)
Grape Vine
Madrona
Manzanita
Maple
Oak
Pear
Pecan
Sycamore
Unsafe Wood
Apricot
Bitter Almond
Boxwood
Cherry
Cherry Laurel
Eucalyptu Evergreen (pine, cedar, redwood, ect)
Hemlock
Laurel
Nectarine
Peach
Plum
Yew
If ever in doubt on what kind of wood you have don't use it, be safe.
I started out using cholla, grapevine and pieces driftwood but the wood would get wet and moldy which is harmful to your crabs. I'd have to take it out often and boil and bake. I started buying wood replicas and jungle vines on line from Pet Discounter. I still use some wood but I use wood replicas and jungle vines to keep them out of the sand, which is much easier and keeps the wood dry.