Under ideal conditions, an optical microscope enables us to observe objects as small as 0.2 micrometer (mm; 1 micrometer is equal to one-millionth of a meter). Although scientists were ...

The top image is a fluorescence micrograph of a dividing solitary choanoflagellate showing its DNA (blue) and flagella and mitotic spindle (green). A small choanoflagellate colony is shown below ...