TYRIAN PURPLE
Tyrian purple was a favorite color of aristocratic Romans (and originally popularized by Julius Caesar and Cleopatra), but its ingredients are less than royal. To create the rich (and expensive) purple hue, thousands of mollusks had to be crushed to attain a single ounce of dye. To affix the color to cloth, dyers had to use a “mordant” or a substance to make the dye colorfast. The Romans’ mordant of choice? Urine. The beautiful clothes may have reeked, but the strange odor became the smell of money to the ancient world. Check out The Brilliant History of Color in Art for more information!
Engraved portrait of Aurelian, Unknown, Roman, A.D. 260 – 280, Amethyst, JPGM.

I thought they like red a lot.