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Plato (left) and Aristotle, detail from School of Athens, fresco by Raphael, 1508-11; in the Stanza della Segnatura, the Vatican. Plato points to the heavens and the realm of Forms, Aristotle to the earth and the realm of things.

Plato and Aristotle: How Do They Differ?

Diverse elementary school children wearing school uniforms running outside of school. Boys girls

Pro and Con: School Uniforms

Santa Claus flying in his sleigh, christmas, reindeer

Was Santa Claus a Real Person?

Secret Service Agent Listens To Earpiece

Secret Service Code Names of 11 U.S. Presidents

Confucius statue at a Confucian Temple in Shanghai, China. Confucianism religion

What is the Difference Between Daoism and Confucianism?

Baseball laying in the grass. Homepage blog 2010, arts and entertainment, history and society, sports and games athletics

10 Greatest Baseball Players of All Time

Saint Lucia Day. Young girl wears Lucia crown (tinsel halo) with candles. Holds Saint Lucia Day currant laced saffron buns (lussekatter or Lucia's cats). Observed December 13 honor virgin martyr Santa Lucia (St. Lucy). Luciadagen, Christmas, Sweden

7 Winter Solstice Celebrations From Around the World

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invertebrate integument

Learn about this topic in these articles:

aragonite

In aragonite
…element in the shells and tests of many marine invertebrates. These animals can secrete the mineral from waters that would ordinarily yield only calcite; they do so by physiological mechanisms that are not fully understood.
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mollusk larvae

In mollusk: Reproduction and life cycles
…protected below a covering (test) of cells provided with one to four girdles of cilia, at the apex of which is a sensory plate of ciliated cells. After the developing juvenile has grown out apically of the test (which then is lost), the animal settles and develops into an…
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