Art,
The ivory was elephant, hippo, walrus, hornbill and sperm whale. (not real sure about the hornbill.
On a fresh killed animal, ivory will be pure white. On a dropped tusk, or an animal that has been dead for some time, the ivory will turn brown on the outside. This is evidenced at Warther's by the samples they have hanging on the wall, and laying around for tourists to pick up as a demonstration of how much ivory weighs. Once the brown spots are taken off, the ivory is white again. The brown is a discoloration of the outside portion of the ivory.
And as bill mentioned, the pliers tree is a group of interconnected wooden whittled pliers. I forgot the number of pliers, but the total number of cuts to create the plier tree was 31,000. When asked by Ripley if he would sell it for Ripley's museum, he replied that he would not make another one like it in a 1000 years, so the answer was no.
Below are a couple pictures I took which should give you an idea of his work, including the Pliers Tree.
Linear Mode
