An article recently published in the “Journal of the Geological Society” describes a research on the fossils of the Lower Fezouata formation in the south-east of Morocco, a deposit discovered only five years ago. These fossils shed light on the evolution of many families of animals in the Ordovician period, between 485 and 444 million years ago. In particular, it shows that some of the oldest animals survived millions of years longer than it was inferred from previously found fossils.