Fossils only form if certain qualifications are met, and some organisms cannot meet them, so they just cease to exist, not a single sign of them. This could happen if they were organisms that decayed completely. Fossilization can include freezing, drying, and encasement, usually in tar or resin.
Answer:
water is evaporated into the air then the water molecules get too heavy and come back down as snow/rain/ect
