Shell Imprints and Fossils

In the garden today we made imprints in modeling clay with shells when we were learning about fossils.they were supposed to look like fossils that you could find. There was a big fossil called ammonite. Some of the fossils were big and some small, but all were very old -duh- they were ONLY 100,000,000 years old that's not much at all for a fossil. Some might have been fossils for 998,998,998 years old (or something like that).