Back in the day, you only knew about microorganisms and viruses that you knew how to grow. And that apparently excludes about 99.9% of stuff. In Biology 101, I

Back in the day, you only knew about microorganisms and viruses that you knew how to grow. And that apparently excludes about 99.9% of stuff. In Biology 101, I recall that we cloned bacteria from sewage, and then cloned a bacteriophage. But the instructors were very careful that we cloned E. coli :)