Teredo Petrified Wood
The Teredo was a worm-shaped mollusk related to clams, mussels, and oysters. It burrowed its way through sequoias and other trees growing near warm-water swamps in North Dakota 60 to 80 million years ago. As the trees in the mineral rich water petrified, some of the wood was replaced by silica and quartz, thereby preserving evidence of the Teredo. North Dakota was not represented in the Smithsonian Institution's mineral collection. Naming of the Teredo petrified wood as the state fossil remedied that situation and promoted the fossil to tourists, geologists, and rockhounds.