Plant fossils are imprints of plants that lived millions of years ago. Specific conditions have to be met for the plants to turn into fossils. One is that they have to die near a lake bed, tar, or clay. These specific materials will help preserve the plant during the fossilization process. Once the plants die and get buried in rocks and sediment, the plant starts to slowly decay. As it starts to decay, minerals from the sediment above it and water start to seep into the space left behind by the plant. This creates an imprint or fossil of the plant. Then, over millions of years, those fossils are buried deeper and then dug up by humans.