Why have fossil's of some extinct organisms have been found and others haven't?

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.

They are two very different tunings. Urination is basically releasing your urine while the other one relates to releasing sperm..