Differential interference contrast (DIC) light micrograph of the freshwater diatom Diploneis sp. Diploneis belongs to the pennate diatoms (penna: Latin for feather). The single cells contain two wall chloroplasts whose brown colour is caused by the dye fucoxanthin. The picture shows a shell view of the cell. The focus is on the outside of the shell with the longitudinal raphe and the fine transverse stripes on the outside of the cell. Magnification: x600 at a print width of 10 centimetres.