Why pollen grains are well preserved as fossil?

Pollen grains:

1. These are microscopic structures that contain the male gamete in them.
2. These are produced in the anthers of a flower.
3. They appear to be powdery grainy substances on the flower.

Pollen grains are well preserved as fossils because:

1. A substance called sporopollenin helps them in being well-preserved.
2. Pollen grains have a two-layered wall out of which the exine in the outer hard layer is formed of sporopollenin.
3. Sporopollenin is one of the most resistant organic materials.
4. It can tolerate extremely high temperatures and strong alkali and acids. There is no enzyme known so far which can degrade sporopollenin.