A eukaryotes is an organism that has membrane bound organelles inside their cells such as the nucleus where genetic material is stored. A prokaryote does not have a nucleus and the main example of prokaryotes is bacteria.
All animals, plants and fungi are eukaryotes. So eukaryotic fossils are fossils of these organisms, so pretty much all the fossils that have been discovered are eukaryotic!
Hope that answers your question 🙂
There are some cool pictures of eukaryotic fossils on this website where you can see the nucleus inside their cells: