Protospongia
Protospongia is a genus of Porifera known from the Middle Cambrian Burgess Shale.Description
Modern sponges are widely agreed to be descendants of the earliest cell colonies that evolved into modern animals. The earliest fossil evidence for sponges are tiny sponge spicules, which first appeared very close to the end of the Proterozoic era. They probably evolved as protection, as well as support, during the great arms race at the start of the Cambrian explosion.
