The case for E. coli

In the midst of a long Freaky Trigger thread about canons, Mark had said "I think you can't make a Canon Of Everything," which I took as a challenge, with this result:

1. Dinosaurs
2. The wheel
3. The way she looked that summer
4. E. coli
5. A. Conan Doyle
6. Napoleon
7. Superwords
8. WTF?
9. China
10. Protein

Sabina has since added: "I like that you kept it to 10, and I would ask you to unpack some of these, except I find I agree with most of them! E. coli, maybe, you could unpack E. coli for the class. XD"

And I replied:

E. coli is a ubiquitous bacterium that enters our intestines (and those of other warm-blooded creatures) within the first forty hours after birth and creates many friends and relations that hang around there being benign and friendly and even doing helpful stuff like manufacturing vitamin K₂, whatever that is (I'd originally read that as "vitamin K₁₂" which I assumed was a vitamin that helped us stay in school until graduation). Apparently these goody-good E. coli also prevent "the establishment of pathogenic bacteria within the intestine."

( But these E. coli creatures are only good because of their environment )