Differential interference contrast (DIC) light micrograph of a Stentor polymorphus freshwater ciliate protozoan together with a Volvox aureus green alga colony. Stentor poloymorphus has a trumpet-like opening surrounded by a rim of cilia (hair-like structures) that beat to draw food inside their gullets. The green colour comes from symbiotic Chlorella sp. green algae. Stentor is a relatively huge single-celled protist and can reach a length of about 2 millimetres. The ciliate's body is wrapped around a Volvox globator algae colony, which is pinched between the slide and the coverslip. Magnification: x100 at a print width of 10 centimetres.