Fossils are rare for several reasons. Most importantly, not all animals’ remains are left to be fossilized. Most animals are food for other organisms, so their bodies may not even be available to be fossilized. Moreover, organisms that die are left to the elements, like wind and rain, which can destroy any remaining evidence of their existence. If an organism is buried by sediments and its remains fossilize, paleontologists have to be able to access the rocks— and access them quickly. Over time the fossils themselves can again be exposed to the elements, destroying what is now pretty rare evidence. Soft tissues, like skin and organs, can be especially difficult because it takes an especially rare set of circumstances to mineralize and preserve these tissues.