Blepharisma ciliate protozoan, coloured scanning electron micrograph (SEM). These tiny single-celled organisms are found in freshwater and marine habitats. It feeds on bacteria and decaying organic matter, which it filters through membranelles in its primitive mouth, known as a buccal cavity (upper centre). The membranelles, rows of fused cilia (short microscopic hairs), are also used for locomotion. Magnification: x500 when printed at 10 centimetres wide.