What is the world's oldest known multicellular animal still living on the planet today?

The oldest evidence of a sea sponge was found in a 760-million-year-old rock. This recent discovery didn't change the status of the sea sponge, as the previous evidence was 635 million years old, which also made it the oldest animal on Earth. It's still possible that even older fossils will be found, but finding an older species is unlikely. The thing is that the sea sponge is the progenitors of more complicated organisms and are sometimes considered to be the ancestors of all the living creatures on the planet.

Sponges are a curious kind of marine animals, as they look like just like plants. There are 5000 different species of sponges in the world. They live in colonies in different depth of the oceans. Their bodies contain of different canals, which allows them to provide shelter for other animal species, living under the water.