Volvox colonies. Light micrograph of colonies of the freshwater green alga Volvox aureus. containing several asexual daughter colonies. The colony is a hollow sphere made up from thousands of cells connected by cytoplasmic threads and arranged in a single layer. Each cell has two flagella, which point outwards, and are used for locomotion. The green spheres within the colonies are daughter colonies, which are produced asexually. Magnification: x40 when printed at 10 centimetres wide.