Or have they? Mostly, yes. Yes, they have.
People love a good puzzle—take a jigsaw. A few hours spent pawing through various pieces, locating all the corners, and matching up colors and figures, all culminating in a completed picture. Very satisfying. Even if the jigsaw is particularly large or difficult, taking longer than a few hours to complete, the sense of achievement (and maybe relief) is a good feeling.
What if there’s a missing piece? It’s disappointing. It’s infuriating. It can ruin an evening or a holiday or, in extreme cases, a relationship. The entries listed below are all fiendishly difficult puzzles that have located their respective missing pieces. Whether it is by advancements in technology, uncovered evidence, or some good old-fashioned logic and reason, we can all rest easier knowing these conundrums have been solved or, at the very least, demystified.
Related: 10 More Unsolved Coded Mysteries You Could Decipher Today
10 Blue Jets
When cinemagoers watched the White House explode under the concentrated energy weapon of an attacking alien spaceship, most were unaware that Mother Nature produced an eerily similar-looking phenomenon—the “blue jets” or ionospheric lightning. Scientists remained in the dark about the cause of this amazing-looking phenomenon. Well, now we know exactly why this happens…sort of.
This amazing aerial phenomenon is, according to scientists using cameras and X-ray detectors on the International Space Station, an upward projecting lightning flash that’s often 48 kilometers (30 miles) long. The cause? “Blue bangs,” a series of blue-hued rumbling bursts in large thunderstorms. There we go—all done.
Except for the fact that we still don’t have a conclusive explanation for the “blue bangs.”
Torsten Neubert, an atmospheric physicist, has posited a hypothesis; short-ranged electrical discharges coming within a half a mile of each other are the cause. The powerful bursts of current result in producing these “blue bangs,” and thus, the “blue jets.”
Either that or it’s aliens.
9 How in the Sweet Hell Does the Flimsy-Looking Butterfly Actually Fly?
It’s no mystery how a bird flies. Indeed, the study of such mechanics laid the groundwork for humankind to take to the skies themselves. Butterflies, however, are complicated. They’re more like a piece of crepe paper caught in an updraft. Scientists have considered the problem of how exactly the little bugs manage to fly for a while but have never come to a firm conclusion. That is, until recently.
A team at Lund University, Sweden, decided to test a 50-year-old hypothesis about how the butterfly flies—the “clap” hypothesis. They found that this is indeed how they do it, using some robotic clappers to simulate the wings. It worked.
It turns out that it is not a simple case of slapping their proportionately huge wings together, though. The little insects have very flexible wings, and only the ends clap together. The remaining portion of the wings creates a small “air pocket,” which aids in propulsion and allows for directional flight.
8 Why Do Japanese Trains Keep Getting Stopped by Millipede Swarms?
Occasionally, up in the forest-covered mountains of Japan, trains are periodically halted in their progress by vast swarms of icky, poisonous millipedes. These events have been recorded as far back as the 1920s, making the phenomenon at least a century old. In 1977, a forestry researcher named Keiko Niijima suggested that it was perhaps a cyclical behavior, speculating that the beasties had an eight-year migratory cycle (similar behavior to that of certain types of bamboo and, more famously, cicadas).
Over 40 years later, this observation has been confirmed as true. As of January 2021, a research team from Shizuoka University has confirmed the eight-year cycle, stating that the migration is due to large broods traveling to new, abundant feeding grounds. Next up—whether the millipedes are planning world domination. In eight years, of course. 
7 When Did Money Get Invented?
This historical head-scratcher has been plaguing academics for centuries. When did people start using money? Well, now we know. Or at least we have a new “earliest date” for items that conform to our modern interpretation of “money.”
Dutch researchers have found that many Bronze Age artifacts—objects shaped like rings, ax blades, and ribs—are mostly the same weight, suggesting that they were interchangeable and used as a form of rudimentary currency. This discovery proves that “money”-oriented commerce was occurring in Europe as far back as 5,000 years ago. Evidence of prehistoric sub-prime mortgages placed on mottle-and-daub huts remains scant. 
6 45-Year-Old Cold Case Solved
Once again, as with high-profile cases like the Golden State Killer murders and the Bear Brooke murders, the guys and gals at Parabon NanoLabs have uncovered the perpetrator in another cold case. This entry is one of the coldest cases to be solved in the U.S. in recent years.
At the very end of that year, December 27th, 1975, police in Grand Junction, Colorado, uncovered the body of a woman who had been bound, raped, and murdered by strangulation in an apartment complex. Forty-five years later, after the case had gone cold decades before, the police department reached out to Parabon for DNA analysis, hoping to get a genetic profile of the killer.
The tests came back, and after some cross-comparisons with criminal databases, police named Jimmy Dean Duncan as the perp. Duncan, who had been 26 years old in 1975, and was also considered a suspect at the time, died in 1987. So while he can never be brought to justice for the horrific crime, the mystery of who killed Deborah has ended, hopefully granting some peace to her loved ones.
These cases give us hope that we can see cold cases becoming a rarity. Maybe even a thing of the past.
5 The Ancient Persian Army That Vanished
People go missing all the time. Although a rarer phenomenon, groups of people will also disappear (think the Roanoke colonists vanishing in 1590). The story of King Cambyses II and his army is a little different. In 524 BC, around 50,000 men disappeared in the Egyptian Sahara. It was as though the sands just swallowed them up. In fact, that was the story for thousands of years—the army was tasked with destroying the Oracle of Amun at the Siwa Oasis when a sandstorm enveloped them, burying them all under the desert sands near Luxor.
In 2009, however, a team of Italian archaeologists discovered a mass of bronze artifacts and piles of bones that seemed to indicate the location of the lost army. Had it been true all along—did they indeed all perish in a sudden, unnaturally large sandstorm? They seemed to indicate as much when revealing their discoveries in a documentary film (which is more Ancient Aliens than The Egypt Exploration Society).
According to Egyptologist Olaf Kaper, speaking on the discovery in 2014, no. the remains were found near a ruined fortress that had been the base for an Egyptian rebel leader named Petubastis III. According to Kaper, the army was probably slaughtered in an ambush reminiscent of the Romans’ defeat in the Teutoburg Forest. It is likely that the arrogance of the invading Persians was their undoing, crushed by a rebel force much more used to the environment and spurred by revenge. The myth of the sandstorm was probably the invention of Cambyses’s eventual successor, Darius I, designed to undermine the reputation of his predecessor and bolster his claim over Egypt.
Given the unlikelihood of tens of thousands of people dying in a single sandstorm, and by applying a bit of Occam’s Razor, it is likely that we can put this millennia-old piece of propagandistic mythmaking to bed.
4 Geometric Problem Solved After 90 Years of Head Scratching
The conjecture in question, made by German mathematician Eduard Ott-Heinrich Keller in 1930, suggests that any tessellation or tiling of Euclidian space by identically sized squares (or hypercubes, when applied to dimensions higher than 2) will always find that two squares will meet face to face. All dimensions, up to the sixth, have been shown to be accurate. The question of the sixth dimension remained too complex to quantify.
That was until a team from Carnegie Mellon University finally crunched the numbers with a bit of help from their computerized pals. After a period of four months of computer programming (and only half an hour to solve the problem), the 90-year-old geometry problem called “Keller’s Conjecture” was solved.
“I was really happy when we solved it, but then I was a little sad that the problem was gone,” said John Mackey, a professor at the university.
Bet you can’t do it again with a pen, a piece of paper, and an abacus, Johnny boy.
3 Missing Link of the T-Rex Identified
Finding the complete lineage of animals that died millions of years ago is a tough gig—a lot of digging involved, followed by tediously long tests that end up with a result that barely makes a blip on the news cycle. If a “missing link” in human phylogeny was unearthed, the world would lose its frickin’ mind.
Luckily for the team involved in this entry, the dinosaur in question is perhaps the best-known and most-loved genus—Tyrannosaurus rex. News emerged back in 2019 that revealed the link between the Jurassic Park star and an erstwhile discovered small dinosaur called Suskityrannus hazelae. This little beastie, first found in New Mexico 20 years ago, is several million years older than its titanic cousin. It stood at almost 1 meter (3 feet) at the shoulder, considerably smaller than the monster that ate that bloke on the loo (watch the 1st movie, gen Z; it’s the only good one in the series).
Perhaps the most important observation is the similarity in the arm’s length for both species—the (relatively) tiny tyrannosaur displayed the same short forelimbs and strong jaw seen in its more famous descendent. This observation suggests that these traits were adopted while the tyrannosaurs were still relatively small, which makes a hell of a lot more sense.Laurence Sterne Trust keeps the solution—if you fancy having a go, they are the ones to contact to verify if your answer is right.
1 Who Was Jacob Klimowsky?
The Nazi theft of artworks, treasures, and artifacts, as well as their penchant for burning books, is well-documented and well-known. What is often overlooked is their destruction of heritage properties and sites. This terrible purging of culture is a hallmark of totalitarian regimes; Mao’s wholesale destruction of Chinese historical sites in order to remold the Chinese people’s idea of national identity is another prime example. The demolition of the Königsberg New Jewish Cemetery in Kaliningrad in 1938 is a lesser-known example of this terrible practice.
The cemetery was opened in 1928, including a beautiful funeral hall designed by noted German architect Erich Mendelsohn. After its destruction, it faded from collective memory, laying as mounds of rubble on a scrubby plot of land for decades. When Jews in East Prussia, a historical society based in Berlin, went to inspect the site in 2010, they discovered something incredible. Among the debris at the site was a single intact gravestone. It belonged to a man named Jacob Klimowsky. The miracle quickly turned into a mystery—members of the society found that nobody could find a record of the man, or even his family name, in the area.
Ten years later, after a good deal of sleuthing, the society located and contacted some of Jacob’s descendants. They had no idea that their ancestor, a WWI veteran on the German side, was buried in Königsberg, much less that his gravestone was the last one left intact. The family provided the society with documents, including photos, of Jacob, allowing them to finally uncover the mystery and help restore this portion of local heritage that was thought to have been destroyed.