@nprofile1q... The creatures revealed in minute detail in the fossils from this shale deposit are like nothing you recognize from the planet today. Life was trying out all sorts of branches, many which no longer exist in any form or have radically evolutionarily diverged. They're essentially alien life forms only from our deep past rather than other planets. Opabiana is one which strikes me as particularly weird.

https://en.wikipedia.org/wiki/Burgess_Shale-type_fauna