We’ve been to the moon, we’ve mapped the continents, we’ve even been to the deepest point in the ocean — twice. What’s left for the next generation to explore? Biologist and explorer Nathan Wolfe suggest this answer: Almost everything. And we can start, he says, with the world of the unseeably small. Nathan Wolfe talks about the so-called “biological dark matter”, perhaps a new form of previously unknown form of life.