If you live near a neighborhood that has lots of trees it can help with air so you can breath so it is healthy and your environment has trees
To actually control the color of their skin, cephalopods Use tiny organs in their skin called chromatophores. Each tiny chromatophores is basically a sac filled with pigment, minute muscles tug on the sac, spreading it wide and exposing the colored pigment to any light hitting the skin.
The large intestine makes bacteria that produce vitamins
