Noriko Okamoto and Isao Inouye of the University of Tsukuba, Japan, discovered a unique microorganism they called "Hatena".
Hatena is unique because it is a snapshot in the evolutionary process of endosymbiosis, where one creature incorporates another, thus creating a new form of life.
These creatures can resemble plants or animals, but during one phase of its life it resembles a predator. At another stage, Hatena carry a green, photosynthesizing alga inside. It divides during that phase, giving rise to two daughter cells — one green and one colorless.
The colorless daughter develops a feeding tool and eventually engulfs another green alga, the scientists wrote.