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earthquake. Heavily damaged school in the town of Yingxiu after a major earthquake struck China's Sichuan Province on May 12, 2008.

The 6 Deadliest Earthquakes Since 1950

Super Typhoon Noru over the western tropical Pacific Ocean as observed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA Aqua satellite July 31 2017

What Is the Difference Between a Typhoon and a Super Typhoon?

A human Inuit skull in a stone chambered cairn in Ilulissat in Greenland. These ancient graves are pre christian and are at least 2000

14 Tough Questions Answered

Mayer Amschel Rothschild (1744-1855), founder of the house of Rothschild; lithograph by Friedrich Lieder, c. 1830.

Where Do Anti-Semitic Conspiracy Theories About the Rothschild Family Come From?

New York NY/ USA- November 23, 2018 Hordes of shoppers throng the Macy's Herald Square flagship store in New York looking for bargains on the day after Thanksgiving, Black Friday.

Why Is It Called Black Friday?

Leonardo da Vinci (1452-1519), Italian Renaissance painter from Florence. Engraving by Cosomo Colombini (d. 1812) after a Leonardo self portrait. Ca. 1500.

10 Famous Artworks by Leonardo da Vinci

Artist interpretation of a Space meteoroid impact. Meteor impact. Asteroid, End of the world, danger, destruction, dinosaur extinct, Judgement Day, Planet Earth, Doomsday Predictions, comet

10 Failed Doomsday Predictions

theca

anatomy and physiology

Learn about this topic in these articles:

Ceratia

In Ceratium
The theca, or armour, is composed of many textured plates that form one anterior horn and usually two posterior horns, which may help to slow the sinking of the cells. The spines tend to be shorter and thicker in cold salty water and longer and thinner…
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vertebrate ovarian follicle

In animal reproductive system: Ovaries
…hagfish, is surrounded by a theca, or sheath, composed of two concentric layers of stromal cells. The outer layer (theca externa) is chiefly connective tissue but may contain smooth muscle fibres. The inner layer (theca interna) has more blood vessels and, in vertebrates that produce heavily yolked eggs, the largest…
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