Polarised and dark field light micrograph of red algae from the Baltic Sea with Vorticella sp. ciliates attached. Algae is usually differentiated based on pigments; red algae contains the pigment phycoerythrin. It is abundant in marine habitats. Despite its name, red algae can vary in colour from bright green to pink, red and purple. There are approximately 6,000 species of predominantly marine algae, often found attached to other shore plants. Vorticella is a genus of bell-shaped ciliates that have stalks to attach themselves to substrates. They eat bacteria and small protozoans and live in fresh or salt water. Although vorticellas are often found in clusters, each stalk is fastened independently. Magnification: 93x when printed 10 centimetres wide.