Question: what is the first creature we have known to exist, that still exists today?

Sean Clement answered on 23 Jun 2011:

Honestly, no-one knows! The fossil record (the evidence of creatures that have existed from what remains of theirs we have dug up) doesn’t extend that far back as far as I’m aware. We think there might be some pretty close relatives still alive today in a group of single-celled microorganisms called Archaea. These are an incredibly varied group of ver simple creatures that are found from the ocean throgh pretty much every type of habitat that you can think of right up to places where we thought no life could exist until not too long ago (Volcanoes, hot springs and super-acidic environments) Given that the earth was a very hostile place 3 billion years ago, these creatures, present in the fossil record dating back a very long time, are probably the best likeness to early life that we know of as they thrive in the only environments left on the planet that bear any resemblance to the early days of the earths history…