Check out the wildest members of the family tree.

Earth is home to an estimated 10 million forms of life, but we can't see most of them with our own eyes. In today's episode, we'll take a peek behind the curtain. We'll explore the bizarre structures, lethal defenses, and fascinating mating habits of bacteria. And we'll finally get introduced to archaea, the newest, oddest, and least understood members of the family tree.