Primordial Ooze

Fossils of blue-green algae have been found in Precambrian rocks known to be more than 4 billion years old. For approximately five-sixths of the time that has lapsed since these organisms appeared, only prokaryotic life existed. Then, approximately six hundred million years ago, an event of profound significance took place; eukaryotic life appeared. Dr. Lynn Margulis of Boston University theorizes that this was accomplished by invasion, wherein a smaller prokaryotic cell moved into a larger prokaryote, took up residence there, and became the nucleus. Until this time-for 3 billion years-the only life on Earth was the primordial ooze that we know as the Cyanophyta: the blue-green algae. If it is correct to assert that all life comes from pre-existing life, perhaps this primordial ooze represents the ancestors of all subsequent life.