<em>Mabui calculus</em> (IMAGE) National University of Singapore Caption Mabui calculus (circled) and substratum of where the crab was found. Credit Tohru Naruse 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.