Acoustic metamaterial (IMAGE) ETH Zurich Department of Physics Caption The experimental sample used for establishing the presence of fragile topological states. The Lego figure is added for scale. Credit ETH Zurich/D-?PHYS Huber group Usage Restrictions None 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.