If you are sneezing this spring, you are not alone. Every year, plants release billions of pollen grains into the air, specks of male reproductive material that many of us notice only when we get watery eyes and runny noses.

However, pollen grains are far more than allergens – they are nature’s time capsules, preserving clues about Earth’s past environments for millions of years.

Pollen’s tough outer shell enables it to survive long after its parent plants have disappeared. When pollen grains become trapped in sediments at the bottom of lakes, oceans and riverbeds, fossil pollen can provide scientists with a unique history of the environments those pollen-producing plants were born into. They can tell us about the vegetation, climate and even human activity through time.