Cyanobacteria, also known as "blue-green algae", are the unicellular organisms which are able to produce oxygen.
Approximately 540 years ago, the atmosphere was very poor on oxygen. Cyanobacteria are thought to be responsible for the oxidization of the atmosphere back then, in an event known as <em>"The Great Oxygenation Event"</em>. As a result, Earth's life forms suffered drastic changes in their composition, as they evolved from being <em>anaerobic</em> to becoming organisms <em>highly dependant</em> on oxygen. The oxygenation of the atmosphere would eventually provide the adequate environment in order for the <em>Cambrian Explosion</em>, or the first diversification of living organisms, to happen.
The invention of the vapor machine
The Catholic Church wanted to end this because taking money for gifts given by the Holy Spirit was seen as a grave sin.
When Pope Urban wanted to wage war against Muslims in the "holy land" Below is a map of the first crusade.
Touissaint L'Ouverture is most closely associated with leading the revolution in Haiti against the French, and helping Haiti win their independence.
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