![A black field with a ctenophore on the left side and a marine sponge on the right side with the word Versus in the middle.](https://qb3.berkeley.edu/wp-content/uploads/2023/05/ctenophore-vs-sponge750x501px-300x200.jpg)
What did the earliest animals look like?
May 18, 2023
For more than a century, biologists have wondered what the earliest animals were like when they first arose in the ancient oceans over half a billion years ago. Searching among today’s most primitive-looking animals for the earliest branch of the animal tree of life, scientists gradually narrowed the possibilities down to two groups: sponges, which…