RedRed is a rare color in nature that is associated with heat sources such as fire, magma and the sun. It is often used to attract attention or to act as a warning.
Sunsets / Sunrises
BlueBlue is the color of water and sky but is quite rare as a color for small scale things.
GreenGreen is the predominant color in nature that is also associated with poison, toxic things and several mythical creatures.
Aliens (in fiction)
Dragons (in fiction)
BlackBlack is the absence of light or the absorption of light. This is extremely prevalent as the color of space and night. Beyond that, black things are somewhat rare except that it is common for people to make things black, particularly fashions and consumer products.
WhiteWhite is the color that is perceived when the mind encounters unbelievably colorful light from a broad range of wavelengths of light. White is pervasive in nature and is an ideal background color as white materials absorb no light.
Sunlight (in space)
BrownBrown is an earthly color associated with soil, rocks, wood and vegetation. It is perhaps the most common color for land animals, birds and food.
OrangeOrange is a rare color in nature that is associated with the few things that are orange such as the freshness of orange citrus fruits. It is also perceived as an Autumn color that is associated with fall leaves and Halloween.
YellowYellow is another rare color with the exception of the sun that is perceived as yellow during the day. Yellow is commonly used by flowers, birds and fruits to attract attention. It is also the color of well known materials including many woods, gold and brass.
Vanilla Ice Cream
PurplePurple is an extraordinarily rare color that is nonetheless a common color for flowers, berries and fruit.