How microbes went nuclear
We try to figure out how eukaryotes, which include everything from single cells to the blue whale, got their nucleus.
Here’s an article about how the nucleus might have originally been a virus.
Here’s something on the inside out theory of the nucleus.
Here’s a bit about how the nucleus might have been an archaea that climb inside another archaea.
Here’s another article about the viral origin of the nucleus.
And here’s a bit about the giant viruses.