There are lots of evolutionary advantages to being colorful.
For example, having different colors on different body parts helps you artfully camouflage yourself in different environments.
Of course, there is also an art to showing the right part with the right color combination in the right place.
Let’s say you are in a grassland area. Everything is brown. The soil is brown. The grasses are brown. The tree trunks are brown. Here, you will want to show only the brown parts of you, such as your shell, so you look like you belong (not like you’ve been catered in for lunch).
But then let’s say you are in a forested area. All around you is vibrant green. There are green leaves, green trees, green grasses, green ferns.
This presents a problem, because you don’t have a speck of green anywhere on you.
One option is to get low and pretend you are part of the soil or just another rock dotting the landscape. If you take this approach, be sure to hide the parts of you that stand out – like, say, your whirling red eyes.
However, sometimes you may be caught out by surprise. There is no time for artful camo. There is no time for anything at all.
Here, there is nothing else for it but to freeze and give whatever-it-is your most ferocious and compelling STARE.

Bruce, you’re the only guy who’s ferocious state is still adorable!
Haha – he pulls it off seamlessly! Sure wish I could learn how he does it 😂