Sporopollenin is a chemically inert biological polymer.
It is a major component of the tough outer (exine) walls of plant spores and pollen grains.
It is preserved in soils and sediments.
Role of sporopollenin:
Sporopollenin is one of the most resistant organic compounds known.
It protects pollen grains from external factors such as temperature, acid, alkali, etc. as sporopollenin is the component of the exine of plant spores.
Due to the presence of sporopollenin, pollen grains are preserved as fossils as these can not be degraded by enzymatic activity.