Reference Terms
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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
August 26, 2026
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Aug. 17, 2026 Nature invented biodegradable plastic long before humans did—and animals may have been feeding on it for hundreds of millions of years. Researchers discovered that dozens of animal species possess ...
Aug. 9, 2026 Deep underground, bacteria may be capable of doing something remarkable: trapping toxic uranium before it spreads. When researchers fed microbes in uranium-contaminated mine water with glycerol, about 95% of the dissolved uranium disappeared within ...
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Aug. 6, 2026 Glyphosate was long thought to be safe for honeybees because they lack the enzyme the chemical targets in weeds. However, researchers found that exposed bees foraged 13 percent less after only three days and showed changes in brain chemicals linked ...
Aug. 4, 2026 Animal bones preserved in South Australia’s underwater caves reveal distinctive clues shaped by darkness, algae, bacteria, and other environmental conditions. The findings give scientists a powerful new way to reconstruct how ancient megafauna ...
Latest Headlines
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Aug. 25, 2026 A sweeping analysis of thousands of animal genomes suggests that chromosomes do not evolve randomly but instead follow a limited number of irreversible “evolutionary highways.” These one-way ...
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Aug. 23, 2026 Scientists discovered a small, yellowish mountain horned dragon in Thailand and named it Acanthosaura syrax after a dragon from House of the Dragon. Found only in a narrow band of high-elevation ...
Aug. 22, 2026 Greenland sharks may live for 400 years without suffering the kind of retinal decline normally associated with aging. Researchers found healthy eye tissue and active proteins specially adapted for ...
Aug. 20, 2026 Scientists have identified exceptionally rare soft tissue preserved in a 450-million-year-old crinoid fossil, more than 200 million years older than ...
Aug. 20, 2026 The human family tree may be due for a major rewrite. Researchers argue that Australopithecus and Paranthropus should be folded into the genus Homo because new fossils have blurred many of the traits ...
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Aug. 17, 2026 Scientists are searching some of Earth’s oldest rocks for tiny fossils that could reveal how simple microbial life made the extraordinary leap toward plants, animals, and other complex organisms. ...
Aug. 16, 2026 Scientists have discovered a new extinct amphibian species hiding in the fossil collections of Los Angeles’ La Brea Tar Pits. Named Spea labreae, the Ice Age spadefoot toad is an exceptionally rare ...