- Any species discovered first as a fossil and believed extinct, but which is later found living; an organism that has remained unchanged over geological periods
- The coelacanth and the dawn redwood are living fossils.
- 2001, "Samurai Jack: The Premiere Movie — Part II: The Samurai Called Jack", season 1, episode 2 of Samurai Jack
- Angus: Impossible! If what you say is true, he'd have to be thousands of years old.
- Rothie: Astounding! The age-o-meter dates your particles all the way back to 25 B.A., twenty-five years before Aku enslaved the Earth. You, my friend, are a living fossil.
- Jack: So the question is not where I am but when I am. […] The spell Aku cast must have ripped me from my own time and flung me into the distant future.
- Any living species which very closely resembles fossil relatives in most anatomical details.
- Crocodiles are living fossils that haven't changed their appearance much in millions of years.