In the Pre-Cambrian era there were no image-forming eyes, and organisms just had basic light receptors to tell the difference between light and dark. For colour to exist there needs to be light, an image-forming eye and a brain to process the data.Around 543 million years ago roughly six major groups of animals existed. Approximately 20 million years later, a blink of the eye in evolutionary history, there were 38 groups - similar to the number that exists today. This dramatic increase may be explained by the evolution of image-forming eyes. With the world suddenly in focus for many species, the benefit of being able to hide oneself, appear threatening or attractive and communicate with one's own species became much more acute.Drawing on spectacular specimens from the Museum's collections, Colour and Vision looks at the evolution of the eye, the uses of colour in nature, from a warning or disguise to an irresistible invitation, and explains how colour works.