coccolith

coccolith

[kok-uh-lith]
noun
a microscopic calcareous disk or ring making up part of the covering of certain marine plankton and forming much of the content of chalk rocks.

Origin:
1865–70; < Neo-Latin Coccolithus originally a genus name; see coccus, -o-, -lith

coccolithic, adjective
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World English Dictionary
coccolith (ˈkɒkəlɪθ)
 
n
any of the round calcareous plates in chalk formations: formed the outer layer of unicellular plankton
 
[C19: New Latin, from Greek kokkos berry + lithos stone]

Collins English Dictionary - Complete & Unabridged 10th Edition
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Encyclopedia Britannica
Encyclopedia

coccolith

minute calcium carbonate platelet or ring secreted by certain organisms (coccolithophores, classed either as protozoans or algae) and imbedded in their cell membranes. When the organisms die, the coccoliths are deposited (at an estimated 60,000,000,000 per square metres [10 square feet] annually) onto the ocean floor and form, along with organic debris, a gray sediment. Fossil forms of coccoliths date from as far back as the Cambrian Period (542 to 488 million years ago).

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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