What is yellow inside of black And what is green and red and black and white inside again?

The phrase "yellow inside of black" often refers to the common depiction of a bumblebee, which has a black exterior with yellow stripes. The second part, "green and red and black and white inside again," could describe a watermelon, which has a green rind, red flesh, and black seeds, often appearing in a white inner layer near the rind. Both descriptions evoke familiar images from nature.