echinochrome

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Cathedrale St.Jean in Lyon, France has a 14th-century astronomical clock that shows religious feast days till the year 2019; Perpetual Calendar

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Aurochs. Bos primigenius. Skeleton. Extinct animal. Skeleton of an Aurochs, an extinct wild ox.

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Gutzon Borglum. Presidents. Sculpture. National park. George Washington. Thomas Jefferson. Theodore Roosevelt. Abraham Lincoln. Mount Rushmore National Memorial, South Dakota.

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Amendments 1-10 to the Constitution of the United States constitute what is known as the Bill of Rights on an American flag.

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US Marines firing at Fallujah, Iraq, during the Second Battle of Fallujah in November 2004. Operation Iraqi Freedom, Iraq War.

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echinochrome

biochemistry

Learn about this topic in these articles:

biological coloration

In coloration: Naphthoquinones
These are the echinochromes and spinochromes, so named because they are conspicuous in tissues and in the calcareous tests (shells) of echinoids, or sea urchins.
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