This was carved from the same piece of spalted oak as the Acorn (large). I deliberately spalted the raw material over a few years. This resulted in the beautiful dark markings that help to highlight the grain of the wood.
Spalting is any form of wood coloration caused by fungi. Although primarily found in dead trees, spalting can also occur in living trees under stress. The unique coloration and patterns of spalted wood are sought after by woodworkers.