When did the phylum Porifera first appear on Earth?

Answer 1

Fossil records clearly show cubozoans dating back to about 350 million years ago. Most scientists think that cnidarians showed up perhaps 700 million years ago since their gelatinous bodies don't lend themselves well to fossilization. That is quite an ancient history for an animal that has the most complicated and sophisticated single cell now in existence, the nematocyte. That cell defines the phylum and can explosively launch a tubule in less than 3ms at an acceleration of about 40,000 times that of gravity, some of which can penetrate almost a millimeter (hundreds of times the length of the nematocyte).

Answer 2

The sponges (porifera) were "predicted" by Darwin, who believed that there must have been earlier and simpler life on earth than the trilobites and such which were the oldest fossils of his time. It was in the late Precambrian era in a period called the Vendian (or Ediacaran) era that the sponges arose. This vast period of time lasted from something around 650 to 540 million years ago. We have found Darwin's suggestion correct in that fossils of proto-sponges and other organisms which were their soft-bodied kin have been turning up in a handful of places. A link is provided to the UC Berkeley post. It's worth the trip to have a look see. The article is easy to read and has the "meat and potatoes" as well as links.

Answer 3

They're said to be appeared about 570 millions years ago.