North Dakota falls in line with Pennsylvania in that it really does not have a State gem, stone, rock or mineral, but it also names a fossil as the State Symbol. Although many charts refer to the Teredo Wood as the state stone, in 1967, the South Dakota Legislature was the first State in the Union to name a Fossil for its Official State Symbol.
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Teredo Petrified Wood bears the boreholes of shipworms, genus Teredo, hence its name. Shipworms are actually a type of mollusc (not worms at all) that were the bane of mariners past and still wreak havoc today on wooden boats and dock posts. During the Paleocene Epoch, about 60 million years ago, North Dakota was partially covered by the last seaway to invade North America, the Cannonball Sea. The swamps and lowlands bordering this sea were home to 50 foot long crocodiles and giant predatory birds. The marine fauna includes bony fish and sharks, crabs, lobsters, snails, and clams. Trees that washed into the sea were frequently attacked by shipworms before they were fossilized, leaving them riddled with holes. This wood belongs to a variety of species, including bald cypress, ginkgo, redwood, and magnolia trees..
Because of the uniqueness of this Petrified Wood, it is collected and worked on by lapidarists and collectors alike in making jewelry, bookends and paperweights. The best collecting sites are in the south-central portion of the state in the Bismarck-Mandan area.
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