An apple. As always, a terrifying morass to paint, with a simple structure that reveals any deficiency in perception or representation of volume or form. Additionally, apples have a texture that incorporates streaks that follow the longitudinal lines of their structure, meaning you have to get the patterns right, as well. Finally, they shift between yellows, greens and reds in their larger markings, while maintaining the relative contrast in streak texture across the larger variations. The recipe, as such, is that you need to use the representation of a fine texture of streaks as displayed over a larger texture of mottling to describe a simple spheroid, and then apply appropriately chosen colors for the highlight over the inititial variations of light and shade on a sphere in order to finally capture the low polish of the texture of apple skin.