Illustration of Hourglass Fermion (IMAGE) Princeton University Caption This is an illustration of the hourglass fermion predicted to lie on the surface of crystals of potassium mercury antimony. Credit Laura R. Park and Aris Alexandradinata Usage Restrictions Credit: Bernevig, et al., Princeton University License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.