Differential interference contrast (DIC) light micrograph of a large terrestrial cyanobacteria (Stigonema mammilosum) often found growing on rocks. Stigonema mammilosum can be found as blackish crusts and biofilms on inselbergs (isolated rock hill, knob or ridge) in many places on earth. Stigonema mammilosum is a filamentous cyanobacteria with true branching (similar to plants) which gives it its characteristic appearance. Magnification: x350 when printed at 10 centimetres wide at its longest edge.