These two organisms are the oldest known signs of life (3.2 billion years).

Currently I am reading "Shattering the Myths of Darwinism" by Richard Milton, and after stating the above, he states a timeframe of 600 million years for the first "microorganisms" to appear.

Debating aside, aren’t Eobacterium and Archaeospheroides microorganisms?

If not, what are they?

I am a bit foggy on the history, but am trying to write an Environmental Biology paper covering the topic of the book.

Thank you!

Henry Perkins

Edit: I’d like to retract my statement by adding Isosphaera (dated back 3.8 billion years) to the list of first known signs of life.