My pieces are more like logs, from 4" to 8" across, 10"+ height, so maybe they have sap or som'thin in'em? Or maybe mine are from really 'old' stuff, because some of mine actually started to fall apart too! Like the insides of the log deteriorates and starts falling apart. Idk, not good luck?! I get mine from PetSmart. It was labeled as manzinita, and if ya look at the one thread I had when I first got some Corys, the wood that the Cory is sitting on, at the top of the tank, that's one of the pieces. Who knows, there's so much 'stuff' mislabeled by that place! Next chance, if I can, I'll try to get some from the source you get yours from, from on this site.