Final answer:
The oldest fossils in the oceanic crust are 3.7 billion-year-old stromatolites from Greenland. Other significant finds include ancient animal fossils dating back 560 to 650 million years in South Australia.
Step-by-step explanation:
The oldest fossils found in the oceanic crust were discovered in Visual sediments in Greenland and are estimated to be about 3.7 billion years old. These fossils are masterstrokes, which are colonial formations created by photosynthetic cyanobacteria. Stromboli fossils worldwide show a decline from between 1 and 1.3 billion years ago. In addition to these ancient masterstrokes, the Acasta Gneiss found in the Northwest Territory of Canada is one of the oldest known Earth rocks, dating back to 3.96 billion years; however, it is not oceanic crust but rather part of the continental crust.
Separately, fossil discoveries in South Australia have revealed the presence of early animal life, including sponge-like fossils that existed some 560 to 650 million years ago. This predates the Ediacaran period and introduces the possibility that animal life evolved during the Cryogenian period. The significance of these discoveries reflects a deeper understanding of the history of life on Earth and challenges previous assumptions about the timeline of evolution.