Decomposition
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40 free Decomposition trivia questions with answers — science & nature quiz, new questions added Oct 2026.
Decomposition is nature's recycling service. Every fallen leaf, dead tree and animal carcass is taken apart by a relay of scavengers, insects, fungi and bacteria, and the nutrients locked inside return to the soil, the water and the atmosphere. Without it, forests would be buried under their own litter. This quiz follows that process from start to finish. It covers the creatures and microbes that do the work, the gases and smells of rot, what happens to a body after death and how forensic scientists read the clues, and the ways people have tried to hold decay back, from ancient embalmers to modern food science. A few questions step into chemistry, where decomposition means one substance splitting into simpler ones. The opening questions suit anyone curious about nature, including biology students revising food chains and nutrient cycles. Later ones go deeper into soil science and forensics. Every answer comes with a short explanation.
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Q 01Which soil animals did Charles Darwin study for decades before making them the subject of his last scientific book?
Earthworms
Earthworms even took Darwin on a trip to Stonehenge, where he studied how their castings had slowly buried the great stones.
Q 02In 1938 California oil workers saw which scavenging birds gather wherever a gas line leaked, drawn by a smell of decay?
Turkey vultures
Turkey vultures hunt by smell, which is rare among birds: they follow ethyl mercaptan, a gas given off as a carcass starts to rot, and traces of it were in the leaking fuel.
Q 03The sunken carcasses of which animals, known to marine biologists as falls, can feed deep-sea creatures for decades?
Whales
Whales that sink deeper than about 1,000 meters become islands of food on the bare seabed, where scavengers, worms and bacteria take the carcass apart in stages over many years.
Q 04Which food never spoils if stored properly, because its sugar and acidity stop most microbes growing?
Honey
Honey traces between 4,700 and 5,500 years old were found on clay vessels in an ancient tomb in Georgia, uncovered while an oil pipeline was being built.
Q 05Which revolutionary leader's embalmed body has been kept from decaying on public display in Moscow since 1924?
Vladimir Lenin
Vladimir Lenin had company for a while: Joseph Stalin's embalmed body lay beside his from 1953 until 1961, when it was removed and buried by the Kremlin Wall.
Q 06Hair and fingernails seem to keep growing after a person dies, but what actually creates that illusion?
Skin drying and shrinking
Skin drying and shrinking away from the bases of hairs and nails leaves more of each one showing; nothing is growing at all.
Q 07The near-instant chemical breakdown of sodium azide into nitrogen gas is what makes which car safety device work?
Airbags
Airbags fill within about 40 milliseconds of an impact; the first to use a small explosion of sodium azide did so in place of compressed air.
Q 08The foaming classroom experiment called elephant's toothpaste shows the rapid breakdown of which household chemical?
Hydrogen peroxide
Hydrogen peroxide breaks down into oxygen and water; adding yeast or potassium iodide as a catalyst makes it happen so fast that soapy foam shoots out of the flask.
Q 09Which everyday kitchen items do soil scientists bury as a standard way to measure how fast plant matter rots?
Tea bags
Tea bags of green tea and rooibos are buried and dug up about three months later; volunteers worldwide have sent in results from tens of thousands of them.
Q 10A bacterium found at a recycling site in Sakai, Japan, can break down and feed on which man-made material?
Plastic
Plastic of the PET family, the material of drinks bottles, is this microbe's food: it breaks down the softer forms and lives on the pieces.
Q 11In 1668 Francesco Redi covered rotting meat with gauze to show that which creatures do not arise from the meat itself?
Maggots
Maggots appeared only on the uncovered meat, never under the gauze: the first real challenge to the old belief that life springs from decaying matter.
Q 12Tollund Man, an Iron Age body found in Denmark with his face and beard stubble intact, was preserved by what?
A peat bog
A peat bog kept him so lifelike that the family who found him in 1950 thought he was a recent murder victim and called the police.
Q 13Which stage of death stiffens a corpse's limbs within hours through chemical changes in the muscles?
Rigor mortis
Q 21Which shiny blue or green insects are usually the first to reach a dead animal, where they lay their eggs?
Blow flies
Blow flies develop at such a predictable rate for a given temperature that investigators use them as a clock to estimate how long a person has been dead.
Q 22Which dark, stable soil material left when plant and animal remains fully decay is named from the Latin for earth?
Humus
Humus can hold 80 to 90 percent of its own weight in moisture, which helps soil that is rich in it to withstand drought.
Q 23What name is given to animals such as millipedes, woodlice and slugs that feed by eating fragments of dead matter?
Detritivores
Detritivores do the first shredding: by breaking dead plants into small pieces they open the way for bacteria and fungi, which cannot swallow lumps of matter.
Rigor mortis does not last: the stiffness fades again over the following days, once the muscle fibres themselves start to break down.
Q 14Which French scientist used swan-necked flasks to show that airborne germs, not spontaneous generation, spoil broth?
Louis Pasteur
Louis Pasteur found that nothing grew unless a flask was tilted so that the liquid touched the contaminated walls of its curved neck.
Q 15Egyptian embalmers removed the lungs, liver, stomach and intestines to stop a mummy rotting and stored them in what?
Canopic jars
Canopic jars came in fours, and later sets gave each lid the head of one of the four sons of Horus, the guardian of the organ inside.
Q 16Which US state was the first to legalize human composting, officially called natural organic reduction?
Washington
Washington also set rules for the result: the composted remains must be tested for toxins including arsenic, lead and mercury.
Q 17William Bass opened the first body farm, where donated corpses decay outdoors for forensic study, in which US state?
Tennessee
Tennessee got the facility at its state university in Knoxville because nowhere then existed for studying how a human body changes between death and decay.
Q 18Body fat in wet, airless graves can turn into adipocere, a crumbly substance nicknamed after which material?
Wax
Wax fits: grave wax, or corpse wax, forms when bacteria break down fat without air, and it can leave a firm, lasting cast of the face and organs.
Q 19Which flammable gas makes up roughly half of the gas given off as buried trash rots without air in a landfill?
Methane
Methane is 40 to 60 percent of landfill gas, which is why many large US sites must at least collect it and burn it off, and some use it to generate electricity.
Q 20Which chemical became the foundation of modern embalming because it preserves body tissue so well?
Formaldehyde
Formaldehyde was discovered by the Russian chemist Alexander Butlerov in the 1850s, and a typical embalming fluid still blends it with methanol and other solvents.
Q 24What is the name for the root-like mass of branching threads through which a fungus spreads and digests rotting wood?
Mycelium
Mycelium can be too small to see or, in the genus Armillaria, a single growth can span thousands of acres.
Q 25Which wood-eating insects digest the cellulose in dead timber with the help of microbes living in their guts?
Termites
Termites turned out to be close kin of wood-eating cockroaches, a link first suggested because the two groups carry similar microbes in their guts.
Q 26Natural history museums use dermestids, which are what kind of insect, to pick animal skeletons clean?
Beetles
Beetles of this family are also called hide or larder beetles, and their larvae turn up on human remains in the dry, late stages of decay.
Q 27Which fossil fuel began as wetland plants that were sealed off from the air before they could fully rot?
Coal
Coal beds are mostly very old: about 90 percent were laid down in the Carboniferous and Permian periods, when wetland forests covered much of the tropics.
Q 28Rotting eggs stink because bacteria release a gas from amino acids that contain which yellow element?
Sulfur
Sulfur gives the gas its stench, and the same gas rises from swamps and sewers where matter decays without air; it quickly deadens the sense of smell.
Q 29Why does Sumatra's titan arum, the so-called corpse flower, give off a powerful stench of rotting flesh as it blooms?
To attract pollinators
To attract pollinators that normally seek out carrion, the bloom also heats up to about 37°C, and its smell can be detected up to 800 meters away.
Q 30Which Swedish chemist tamed nitroglycerin, whose explosive breakdown a mere shock can trigger, by soaking it into earth?
Alfred Nobel
Alfred Nobel settled on diatomaceous earth, a powder of fossilized algae from the Elbe River near his Hamburg factory, and the stable result was dynamite.