To mimic the background color of this book cover ... a subtle pink halo around the heart with unpigmented E. coli. These bacteria fermented the lactose in the agar and turned pink due to the pH ...

The saltier the water, the more Dunaliella salina it grows, leading to a deeper pink color. Bacteria, such as Haloarchaea, contribute to the vivid color as well, intensifying the pinkish-red ...

Chicks hatch with white feathers that turn gray—and later take their pink color from aqueous bacteria and beta-carotene obtained from their food. Although flamingos have become a visual cliché ...