Getty Images, photo by Handout

Research has been done to determine the smell of Earth 1.9 million years ago using tiny fossils from rocks around Lake Superior, Canada.  The fossils of ancient microbes show the discarded leftovers of early meals showing a type of feeding on organic matter was taking place.

 Microbes feasted on bacteria called Gunflintia and evidence showed this type of feeding dates back 3.5 million years. Scientist say modern bacteria feed almost the same way as millions of years ago and we have all smelled that stench, hydrogen sulfide.  Basically early Earth smelled like rotten eggs!

Indiatimes.com