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Reference.org
Outline of life forms
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<p>The following <a href="/facts/Outline_(list)/uUpf6Jh6">outline</a> is provided as an overview of and topical guide to life forms: </p><p>A life form (also spelled life-form or lifeform) is an entity that is <a href="/facts/Life/DNw7NUId">living</a>, such as plants (<a href="/facts/Flora/2xkcTn2d">flora</a>), animals (<a href="/facts/Fauna/sMqPFxVD">fauna</a>), and fungi (<a href="/facts/Funga/cDhUKckw">funga</a>). It is estimated that more than 99% of all species that ever existed on Earth, amounting to over five billion species, are <a href="/facts/Extinction/24p5NP2q">extinct</a>. </p><p><a href="/facts/Earth/HLLmDfj0">Earth</a> is the only celestial body known to harbor life forms. No form of extraterrestrial life has yet been discovered. </p>