4.1-billion-year-old crystal may hold earliest signs of life
![zircon crystal](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2015/10/101915_ts_jackhills-ticker_rev-1.jpg?fit=860%2C460&ssl=1)
Life on Earth appeared before 4.1 billion years ago, new research suggests. This ancient zircon crystal contains a small carbon impurity (indicated by arrow) associated with organisms.
E.A. Bell et al/PNAS 2015