What are these mysterious organisms living on the hull of the International Space Station? How did they get there? And how can they survive in space? Is this evidence that life on Earth originated elsewhere? Or is it evidence that life on earth is able to find its way elsewhere? Or both?

Also: The complete story of Kennewick Man. Is a lot of what we know about human settlement in North America incomplete...or just plain wrong?

Plus: The cat who wasn't there. Or who was there, but wasn't a cat. (Or something.)

Tune in and explore.