ABSTRACT This study was conducted from October-November 2019, located in Batang Masang River Estuary Village Tiku V Jorong Agam, West Sumatera. This study aims to understand community structure of epizoic diatoms in snail shells Cerithidea cingulata. The method used in this study was a survey method. Identification diatom was conducted at the Marine Biological Laboratory Marine Science Fa…