Pearls form when a saltwater oyster or a freshwater mussel coats a parasite or other irritant that has entered its shell with concentric layers of calcium carbonate and organic protein.

Stony corals form a type of calcium carbonate called aragonite from ions brought to the ocean by rivers that have broken down terrestrial rocks.

Ocean salinity comes primarily from eroded rocks, whose salts and minerals are carried into the sea by runoff, and from seawater dissolving salts and minerals from magma at seafloor openings.

Rocks, crystals, and gemstones are all made of minerals—solids that form from natural processes, such as evaporated water leaving salt behind or lava rapidly cooling into a solid.

Coral reefs are built by thousands of coral polyps—tiny animals whose mouths both consume food and expel waste.

The three types of coral reefs—fringing, barrier, and atoll—are categorized by where they form.

Since the Industrial Revolution, surface ocean waters have become 30% more acidic due to the absorption of carbon dioxide, which disrupts the formation of coral reefs and the shells and skeletons of marine organisms.

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

The first coral reefs formed hundreds of millions of years ago from the carbonate skeletons deposited by hard corals.

How chefs suspend liquid in edible pearls resembling caviar to introduce a new texture to fluids

Through spherification, drops of a solution of sodium alginate and a flavored liquid are placed in a calcium lactate solution, which forms a chemical skin around them. This is because calcium replaces the sodium in the alginate chains, forming a gel around each drop's liquid interior.

Deep water corals—located throughout the world's ocean basins at depths beyond 200 meters (660 feet)—slowly build small coral gardens in the dark with the help of underwater worms.

As immobile animals, corals and the organisms that live on them have evolved a suite of chemical compounds to prevent disease and ward off predators they cannot outrun.

Distinguishing the three types of mineral deposits collected via deep-sea mining

The greatest interest is in polymetallic nodules—structures formed from metals in seawater collecting around a core of shell, bone, or rock. Cobalt-rich ferromanganese crusts cover underwater mountain ranges and form over millions of years of metal deposition. Polymetallic sulfide deposits accumulate when seawater seeps into volcanic rocks.

Scientists have collected critical minerals from ocean water using seaweed, a type of algae that leaves behind a mineral-rich powder called bio-ore after being processed into biofuels.

Rather than removable armor like snail shells, turtle shells are part of the organism's skeleton and consist of 50 to 60 fused bones that grow with the organism.

Sea stars are invertebrates—they lack a backbone—and while most exhibit pentametric radial symmetry due to having five arms radiating from a central disk, some can possess more than 40.

Light pollution is giving oysters insomnia

Oysters, bivalve mollusks that have light-detecting cells along their skin, can't sleep with all this artificial light. According to a 2022 study, oysters' sleep cycles are disturbed by light dimmer than that provided by the full moon. As with humans, it's possible that these bouts of insomnia could have adverse health effects and contribute to the development of disease over time.

As crystals form, their properties and the shapes they take on, including cubic, tetragonal, and hexagonal patterns, reflect the arrangement of their constituent atoms.

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.

View a gallery of diatoms—algae surrounded by glass-like shells—captured via microscope.

Over 1 million fish, marine mammals, and invertebrate species depend on coral reefs for habitats, camouflage, and food.

Artificial coral reefs have been 3D printed from nontoxic, biodegradable terracotta clay, which coral polyps have used as a foundation for rebuilding marine ecosystems.

Geode formation begins with trapped gas bubbles in igneous or sedimentary rock

Over thousands or millions of years, water seeps into the cavity created by the bubble and deposits minerals, which slowly build and crystallize into quartz, agate, amethyst or other crystals.

Mermaid tears are a long-lasting and hazardous form of ocean microplastic pollution, whose chemical composition enables them to contain higher concentrations of certain toxins than the surrounding environment.

Research has shown that some marine life can survive the extreme pressure of the deep ocean because of specialized molecules that strengthen proteins, enzymes, and cellular membranes.

Coral polyps reproduce via broadcast spawning, where entire reefs simultaneously release reproductive cells for about one hour, once a year.

Salt is harvested from briny ocean water and underground deposits

Mostly sodium chloride, this compound is produced for human use by collecting seawater in shallow pans and allowing the Sun to evaporate the water until crystals remain. Underground rock salt is mined, crushed, and purified from deposits left behind by ancient seas that have dried-up.

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.

Diamonds have been made from substances such as peanut butter and carbon dioxide, though they can be created from any carbon-rich material under extreme pressure and temperature.

Niagara’s bedrock holds 440-million-year-old coral fossils

The Lockport Dolomite that caps Niagara Falls is composed of fossilized coral reefs from a tropical sea that once covered the region 440 million years ago.

An analysis of fossilized reefs from northern Africa and Germany suggests that shallow water corals and photosynthetic algae formed the mutualistic partnership seen today between 419 and 359 million years ago.

Diatomite, a sedimentary rock used as a filtration material in beer, wine, swimming pool water, motor oil, and pharmaceuticals, is formed from the fossilized shells of diatoms, a type of algae.

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

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

Starting with red, colorful objects will appear to lose their colors the deeper they are submerged because water scatters light, reducing the amount available to reflect off objects and be observed.

Watch a time-lapse of staghorn coral polyps—a type of hard coral—over several weeks in an aquarium, slowly forming the foundational component of a coral reef.

Structures from ancient Rome have endured for millennia because tiny pieces of lime in Roman concrete enabled it to self-heal and prevent cracks from spreading when exposed to water.

Japanese scientists have developed an eco-friendly plastic that naturally dissolves in hours, leaving behind molecules containing phosphorus and nitrogen, which fertilize soil.

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.

Climate change threatens coral reefs by disrupting the symbiotic relationship between corals and algae due to rising ocean temperatures.

Synthetic pheromones may protect coral reefs by attracting their predators

Researchers in Australia and Japan have developed these nontoxic chemicals to attract crown-of-thorns starfish, which consume corals that make up the Great Barrier Reef. As of 2026, synthetic pheromones have been shown to be effective in lab trials, and future field trials will attempt to lure starfish into areas for mass removal.

Why 75% of ocean animals glow

About 75% of ocean creatures can make their own light. It's called bioluminescence—and it all comes down to a special chemical reaction happening inside their bodies.

Explore the chemical compounds found in fireworks

Besides the various salts and metals used to produce fireworks colors, shells are also filled with gunpowder and oxidizers to help fuel and accelerate reactions. Chlorates help strengthen colors, while dextrin, a starch, helps hold mixtures together.

Multiple species exhibit convergent evolution by developing crab-like features

Various organisms that appear to be different types of crabs, such as porcelain crabs and coconut crabs, have been shown to belong to distinct decapod lineages whose predecessors resemble shrimp or lobsters. Environmental pressures and other factors have caused these species to develop similar characteristics, which nature has shown are beneficial to survival.

Through coral IVF, researchers have collected coral eggs and sperm from healthy reefs, grown baby corals in lab pools, and then released them to help repopulate damaged or lost reefs.

How diamonds form in the deep earth

Deep within Earth's mantle, diamonds form from carbon-bearing fluids. The formation of these beautiful gemstones, the only direct samples we have of the mantle, helps scientists uncover how carbon functions deep inside our planet. Understanding this complex process aids in the exploration for new diamond deposits.

Fish populations in the Great Barrier Reef have increased after installing waterproof speakers on the ocean floor that played recordings of sounds from healthy coral reefs.

38 thought-provoking facts about the ocean

Coral produces its own sunscreen, tsunamis move at 500 miles per hour, one of the loudest sounds ever recorded came from an ice quake, and other interesting facts collected from sources such as National Geographic and NASA.

Plastic debris across the ocean aids the spread of invasive species

The durable, long-lasting material can serve as a platform for living organisms to latch onto and ride over vast distances. After the 2011 earthquake and tsunami in Japan, a large dock carrying 100 tons of living organisms native to Japan washed up on Oregon's coastline, confirming the ecological threat.

An overview of the metals obtainable through deep-sea mining of nodules and crusts

Polymetallic nodules are a source of manganese, cobalt, nickel, copper, molybdenum, and platinum, which are used in batteries, fuel cells, and metal alloys of electric vehicles. Seamount crusts contain rare-earth elements deemed essential to US national and economic security, including neodymium and dysprosium used to make permanent magnets.

Instead of bones, shark skeletons have 200 to 400 structures composed of cartilage—the same material that makes up human ears.