Copper, not bleach, is responsible for turning some blonde hair green in swimming pools—a phenomenon known as chlorotrichosis.

Bruises go from blue-purple to yellow-green because of a breakdown of hemoglobin—the pigment that carries oxygen throughout the human body.

Bright blue fireworks are the most difficult color to create

Stress contributes to gray hair because when the body experiences stress, the sympathetic nervous system releases specific hormones that influence pigment-producing cells.

El Niño makes the equatorial Pacific Ocean bluer than usual as high temperatures kill off microscopic plants that normally give the waters a green hue.

Water is naturally tinted with a slight blue, but sediments and organics can alter its color

Harmful algal blooms can occur in warm, nutrient-rich, stagnant waters and are often associated with the rapid reproduction of blue-green algae—a misnomer for cyanobacteria, not algae.

Blood can be blue, green, magenta, or transparent due to differences in the oxygen-carrying respiratory pigments they contain.

The same pigments that enable photosynthesis—chlorophyll a and b—are also responsible for giving most plants their green color.

Blood color differs across the animal kingdom, with some animals producing blood that appears green (a group of lizards in New Guinea) or blue (horseshoe crabs).

Ear infections can arise from chlorinated water, too

Lead, arsenic, uranium, and other toxic elements were once used in pigments for producing vibrant colors.

When bleach comes into contact with oily skin, it forms soap—the combination of an alkaline, non-acidic substance with a fat.

Some organisms' colors come from structural color—tiny structures that distinctly scatter different colors of light, eliminating some while reinforcing others that become visible.

The majority of the 100,000 natural compounds that produce colors are pigments, which can be categorized based on their chemical structure.

Corals sacrifice their food source and expel colorful microorganisms to protect themselves during coral bleaching—a phenomenon that resembles an organism's immune system attacking itself.

See how fireworks are made and which metals are responsible for different colors.

Incinerated skeletons, animal blood, and fermented animal waste were among the ingredients used to make the pigments in some of art history's most famous paintings.

'Watermelon snow'—patches of pink, orange, and red in snow—is the result of extremophilic green algae that thrive in extremely frigid conditions and take the shape of red spheres in winter.

Wood that changed the color of water was the earliest recorded example of fluorescence

Blacklights can illuminate certain biological materials, including blood, teeth, and fingernails, because they contain fluorophores—molecules that visibly glow immediately after exposure to higher-energy light.

A 1943 mustard gas disaster in Italy helped scientists learn that certain sulfur compounds can destroy white blood cells, an advance that led to modern chemotherapy.

Coral reefs get their colors from zooxanthellae—photosynthetic algae that line corals' digestive tracts and provide them with sugars in exchange for a home.

Tennis balls are yellow, partly thanks to a suggestion by British naturalist and broadcaster Sir David Attenborough.

A simple infographic explaining how coral bleaching works

Some organisms can change color by quickly revealing or hiding various pigments, as seen in octopuses, squids, and other cephalopods.

How David Attenborough's work in color television gave tennis balls their color

The chlorophyll in plants captures energy in the form of red and blue light

Molecules derived from algae can be found in foods such as ice cream, salad dressings, brownie mix, and gravies, as well as in products such as toothpaste, multivitamins, and egg substitutes.

Massive blooms of microscopic algae called dinoflagellates produce the neon blue light seen in glowing tides.

The world's oldest known synthetic pigment—Egyptian blue—was created about 5,000 years ago.

We can get food poisoning from spending time in swimming pools, lakes, rivers, and ponds

Egg yolks and carrots have the same pigments that contribute to the yellow and orange colors of fall foliage.

Watch underwater photosynthesis make water look like champagne

Some corals absorb harmful ultraviolet radiation and re-emit it as visible light, thereby protecting symbiotic algae within their tissues and providing them with energy for photosynthesis.

Virtually all plants are biofluorescent because their photosynthesis is powered by chlorophyll, a pigment that glows red as a way to get rid of excess energy when exposed to ultraviolet light.

The Great Salt Lake's distinct dual coloration results from high-salinity organisms that only live in the northern portion and produce a purple protein.

See examples of hyperaccumulators, the plants that can harvest heavy metals

Leaves have orange and yellow pigments year-round, but they are masked until the fall, when shorter days reduce the production of chlorophyll, a green pigment.

Research has found that when their symbiotic algae are not producing oxygen via photosynthesis, corals twirl hairlike structures to circulate water and draw oxygen into their outer tissues.

Without liver bile, human poop would be a pale silver color

Eight years after receiving an eyeball tattoo, a patient's swim in the Mediterranean set off rare complications that caused pigment clumping and cornea issues.

Studies of tattoo inks have identified over 100 pigments, which have historically included toxic metals but now include organic compounds.

Flamingos get their pink color from pigments in their food, but they cannot be any color because their bodies cannot process every type of pigment.

Instead of consuming water and carbon dioxide to produce oxygen and sugar, anoxygenic photosynthesis involves alternative reactants and products.

Although rare, HFMD can spreads in pools due to poor bathroom hygiene

Particles moving faster than the speed of light give nuclear reactors an eerie blue glow.

Swimming in a pool of spent nuclear fuel is safe, as long as you don't drink the water or touch radioactive waste.

Jaundice, which can make the skin and eyes appear yellow, is a buildup of bilirubin, a waste product that forms when old red blood cells break down.

A remote Scottish island is awash in forever chemicals even though there are no obvious industrial sources nearby, and scientists suspect the toxic substances are accumulating via sea spray.

Cholera was called the 'Blue Death'