Figure 64. Teredo-bored petrified wood became North Dakota's official state fossil in 1967. (ND Geological Survey)
STATE FOSSIL. The state fossil of North Dakota is the 60-million-year-old Teredo- (ter-Ee-doe) bored petrified wood. Teredo-bored petrified wood got its name because little clams called “teredos” drilled tiny holes into the wood before it fossilized. Minerals filled in the cells of the wood as it decayed so that it looked exactly like the wood that had been there in the first place, except it was now stone.