Oldest sea sponge fossils found in Australia

American scientists have discovered the ancient fossils of a sea sponge which may prove one of the oldest life forms on Earth.

Just one centimeter in diameter, the tiny creature was found in ocean reefs off the Australian coast were it existed some 650 million years ago.

Characteristic of the sponge was its persistence, scientists say, adding that it easily survived severe frosts that occurred on the planet at that time.

Previously, it was thought that the oldest known primitive animals lived around 550 million years ago.