You can get other colors from biological sources, and ground-up insects, mollusks, and even dried-out poops have been used in the past. It’s very easy to go too far: a shade of yellow called “Indian yellow” was once made by feeding cows only mango leaves until they were so malnourished their urine turned a bright yellow, and a favorite shade in 1600s CE Europe called “mummy brown” was made by grinding up ancient mummies (feline and, yes, human) to paint with their remains.
