Overview of research (VIDEO) Optica This video is under embargo. Please login to access this video. Caption Raphael A. Guerrero provides an overview of the process used to create diffraction gratings from crab shells. Credit Raphael A. Guerrero, Ateneo de Manila University Usage Restrictions None License Original 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.