Yes, that is a good question and I am glad to hear it. Please, guys do not believe everything your teachers say.

Anyway, there are some clues to find out how an ammonite was:

  • It is very rare to find a fossil and it is even more rare to find soft tissues fossilized, but in fact they exist.
  • Furthermore, some extra information comes from evolutionary studies, similar actual organisms, or according to where the fossil was found and what was there too.  So it is assummed that this was its shape not because a very creative scientific made it up but beacause of a multidiciplinar work setting and hypothesis based on their knowledge and some very odd and lucky fossils too.


Information to solve this doubt is also quite clear here.

Are you wondering how soft tissues fossilize? Then, here you have a scientific article to answer your doubts.