 Sponges are among the oldest fossils on earth and the longest lasting modern phylum of animals. The oldest recorded sponge fossil was called "Paleophragmodictya" and lived during the Precambrian Era, approximately 570 million years ago. to date, there are over 900 recorded species of fossil sponges. According to fossils, Poriferan diversity peaked during the Cretaceous Period. The only problem with studying Poriferan history with fossils is that many species of sponges do not have a skeletal structure that will fossilize, meaning that the data that humans have collected regarding ancient sponges is likely much fewer and less diverse than what really was. In addition, scientists have discovered several distinct groups within the phylum that have become extinct millions of years ago. Many of these species are still a mystery as to what they evolved from and if they simply died out or if they evolved into something else.  This is not Paleophragmodictya...  This is Paleophragmodictya |