Fruit anatomy forms the edible tissue around the seeds. In other fruits such as "Citrus" stone fruits ("Prunus") only some layers of the pericarp are eaten. In accessory fruits, other tissues develop into the edible portion of the fruit instead, for example the receptacle of the flower in strawberries. In fleshy fruits, the pericarp is typically made up of three distinct layers: the epicarp (also known as exocarp), which is the outermost layer; the mesocarp, which is the middle layer; and the endocarp, which is the inner layer surrounding the ovary or the seeds. In a citrus fruit, the epicarp and mesocarp
Earliest known life forms Australian Apex chert rocks. A life form, or lifeform, is an entity or being that is living. Currently, Earth remains the only place in the universe known to harbor life forms. More than 99% of all species of life forms, amounting to over five billion species, that ever lived on Earth are estimated to be extinct. Some estimates on the number of Earth's current species of life forms range from 10 million to 14 million, of which about 1.2 million have been documented and over 86 percent have not yet been described. However, a May 2016 scientific report estimates that