One of my recent projects involved investigating a small family of new perovskite materials under pressure. We used in situ single crystal diffraction on the I19 Beamline at Diamond Light Source. We found that one of the two systems behaved rather strangely – one expanded in one direction while reducing in overall volume from ambient to increasing pressure. This is the first example of a hybrid perovskite showing this behaviour, explore how and why by reading our open access article in ChemComm.