And Finally...

For the first time in at least a billion years, two lifeforms have merged into a single organism.

The process, called primary endosymbiosis, has only happened twice in the history of the Earth, with the first time giving rise to all complex life as we know it through mitochondria. The second time that it happened saw the emergence of plants.

Now, an international team of scientists have observed the evolutionary event happening between a species of algae commonly found in the ocean and a bacterium.