These fossils appear to be photosynthetic, however, suggesting that the earliest life probably had evolved prior to that of 3.5 billion years ago. One of the essential episodes in the formation of life on Earth involved the formation of a selectively permeable membrane that could enclose a solution of different composition from the surrounding solution, therefore providing a stable environment, while still allowing exchanges of nutrients and wastes. The formation of the biological membrane and its selective permeability to various substances is the one most important factor that led to the origination of life. However, this formation, despite its importance, is quite simple. When phospholipids are mixed with water, they self-assemble to form films due to insolubility.
Agitation then breaks the films into sphere.
Even these primitive membranes have some ability to control the passage of substances between the contents of a sphere and the aqueous environment outside. The prokayrotes are the single-celled organisms that have successfully acquired the biological membrane system, but lack the endomembrane systems found in the more advanced eukaryotes. The prokaryotes thus were the earliest organisms, and they lived and evolved all alone on Earth for 2 billion years. The eukaryotes, on the other hand, are more advanced with endomembrane systems. Other examples include the engulfing of golgi apparatus, mitochondria, etc.