The prior oldest known hard-bodied animals were reef-dwelling organisms called Namacalathus, which date to approximately 550 million years ago. Disputed remains for other possible soft-bodied animals date to between 577 and 542 million years ago.
The even more advanced age of the newly found sponge fossils provides direct evidence that animal life existed before the severe “Snowball Earth” event. The episode marked the end of Cryogenian Period 635 million years ago and left much of the globe covered in ice.
The early sponges somehow managed to survive, perhaps in watery refuges around volcanic islands.
“The sponges were about one centimeter (0.4 inches) tall and probably lived on hard stromatolite reefs made by bacteria,” lead author Adam Maloof told Discovery News.
“The sponges probably swayed in the ocean currents in less than 20 meters (65.6 feet) of water filtering organic carbon out of the water for food,” added Maloof, a geosciences professor at Princeton University.