This article is about a thing that is living or alive. For The Future Sound of London album, see Lifeforms (album). For other uses, see Lifeform (disambiguation). A life form or lifeform is an entity or being that is living or alive or living. This is a list of articles that relate to physical, hypothetical, alleged, religious, or fictional life forms. Although more than 99 percent of all species that ever lived on the planet are estimated to be extinct, there are currently 10–14 million species of life on the Earth. In process philosophy, objects in the world or universe are layered or tiered in complexity. Living things are difficult to define, but life forms can be considered to be the most complex entities in the arena or environment in which they exist. As in process philosophy, this article brings together in a holistic manner, life forms from the diverse human intuitions found in experiences that include the ethical, religious, philosophical, scientific, and aesthetic.