One way to delve deep into the ancient history of the Earth - or other planetary bodies for that matter - is to examine the magnetism recorded by rocks. Kind of like a fossilised magnetic fingerprint. But trying to do this in an environment where another magnetic field exists (i.e. everywhere on Earth!) is pretty challenging. Enter the 'magnetically shielded room'! Join us as we catch up with Prof James Bryson from Oxford's Department of Earth Sciences, and find out all about this very special DIY project.