yeah the bark is what your gonna be looking for, nothing else like it. Ive seen it almost slick, with very few "warts" here and there, and ive seen it packed on thick, where all the warts form vertical ridge type structures that all run together.
an individual wart sort of resembles what you would expect a topographical representation of an island would look like. The wart looks like its made from progressively smaller rings near the top, as opposed to the bottom that is attached to the tree. some are cone shaped, some are like a plateau, some are just irregular all together. And like i said, some are lined up so thick they look like they all run together in vertical strips. Usually on bigger trees the entire surface of the bark is clustered with these warts. The smaller ones tend to have less.