Official State Fossil of North Dakota
North Dakota designated teredo petrified wood as the official state fossil in 1967 (one of the first states to recognize a fossil symbol). Naming Teredo petrified wood as the state fossil promoted the fossil to tourists, geologists, and rock-hounds, and caused the Smithsonian Institution to represent North Dakota in its mineral collection. Petrified wood is also a symbol of Washington, Louisiana, and Texas. All State Fossils
Teredo petrified wood is unique because of the "worming" of the original wood by the prehistoric teredo - a worm-shaped mollusk related to modern clams, mussels, and oysters. 60 to 80 million years ago during the Paleocene Epoch, the teredo was burrowing through trees growing near the edges of warm swamps in North Dakota.