Reference Terms
from Wikipedia, the free encyclopedia
Animal shell
A shell is a hard, rigid outer layer, which has evolved in a very wide variety of different animals, including mollusks, sea urchins, crustaceans, turtles and tortoises, armadillos, etc. Scientific names for this type of structure include exoskeleton, test, carapace, and peltidium.
The shells that are perhaps most familiar and most commonly encountered, both in the wild and for sale as decorative objects, are seashells, more precisely, the external shells of marine mollusks. These are usually primarily composed of calcium carbonate, in the form of calcite or aragonite crystallised out in an organic matrix. Calcium carbonate in mollusc shells can take different crystalline forms, one being nacre otherwise known as mother of pearl.
Other kinds of animal shells are made from chitin, bone and cartilage, or silica.
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Plants & Animals News
February 23, 2026
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Feb. 18, 2026 As the planet warms, many expected ecosystems to change faster and faster. Instead, a massive global study shows that species turnover has slowed by about one-third since the 1970s. Nature’s constant reshuffling appears to be driven more by ...
Feb. 17, 2026 Researchers investigating crops grown in soil contaminated by the 2015 mining disaster in Brazil discovered that toxic metals are moving from the earth into edible plants. Bananas, cassava, and cocoa were found to absorb elements like lead and ...
Feb. 16, 2026 Even Antarctica’s toughest native insect can’t escape the reach of plastic pollution. Scientists have discovered that Belgica antarctica — a tiny, rice-sized midge and the southernmost insect on Earth — is already ingesting microplastics in ...
Feb. 14, 2026 A new study shows that dogs and cats may be helping an invasive flatworm spread. Researchers analyzing over a decade of reports discovered the worm attached to pet fur. Its sticky mucus and ability to reproduce alone make it highly adaptable. Pets ...
Feb. 14, 2026 Scientists are launching an ambitious global effort to map the “human exposome” — the lifelong mix of environmental and chemical exposures that drive most diseases. Backed by new partnerships with governments, UNESCO, and international science ...
Feb. 12, 2026 A new scientific review challenges the headline-grabbing claim that Yellowstone’s returning wolves triggered one of the strongest trophic cascades on Earth. Researchers found that the reported 1,500% surge in willow growth was based on circular ...
Feb. 12, 2026 Coral reefs, worth an estimated $9.8 trillion a year to humanity, are in far worse shape than previously realized. A massive international study found that during the 2014–2017 global marine heatwave, more than half of the world’s reefs suffered ...
Feb. 10, 2026 Life’s story may stretch further back than scientists once thought. Some genes found in nearly every organism today were already duplicated before all life shared a common ancestor. By tracking these rare genes, researchers can investigate how ...
Feb. 9, 2026 Forests around the world are quietly transforming, and not for the better. A massive global analysis of more than 31,000 tree species reveals that forests are becoming more uniform, increasingly dominated by fast-growing “sprinter” trees, while ...
Feb. 8, 2026 Your gut is home to trillions of bacteria that constantly “sense” their surroundings to survive and thrive. New research shows that beneficial gut microbes, especially common Clostridia bacteria, can detect a surprisingly wide range of chemical ...
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Feb. 23, 2026 A century after Erwin Schrödinger sketched out a bold vision for how we perceive color, scientists have finally filled in the missing pieces. A Los Alamos team used advanced geometry to show that ...
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Feb. 22, 2026 Triceratops’ massive head may have been doing more than just showing off those famous horns. Using CT scans and 3D reconstructions of fossil skulls, researchers uncovered a surprisingly complex ...
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