Worthenia

Worthenia is a genus of fossil sea snails, an extinct marine gastropod genus found in the fossil record. This genus is primarily found in rocks formed during the Devonian to Triassic periods (416 million to 200 million years ago) from the central areas of North America. Worthenia species have a `turban-shaped shell in which a raised ridge follows....
Found on http://en.wikipedia.org/wiki/Worthenia

Worthenia

genus of extinct gastropods (snails) preserved as common fossils in rocks of Devonian to Triassic age (408 to 208 million years old) but especially ...
Found on http://www.britannica.com/eb/a-z/w/54
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