Wood rot in reptile cage?

i purchased drift wood from Pet Suppliesplus a week ago. Its called malaysian driftwood, its made by Zilla. it says that it is used for terrestrial and aquatic enviornments and it is also water resistant. i have the drift wood in my dragons water dish so half of it is submerged while the other half is not. when i was cleaning his cage i inspected the wood to see how it looked and on inspection i saw little green dots on the wood. i suspect mold. if this is true then does it mean the wood is not resistant to water? also can i treat the drift wood myself? if i can i need a way to stop it from molding and to not be poisioness to my little dragon. any info will be appriciated!!