Researchers have found bacteria that live in rocks 2.8 kilometers below Earth's surface and rely on radioactive uranium to convert water molecules to useable energy.

The theory that a meteor impact near modern day Mexico killed the dinosaurs was a staple of my childhood education. However the theory is increasingly falling out of favour. The latest nail in the coffin: the big rock smacked us 300,000 years too early to account for the mass extinction of the dinosaurs.