Again and again, hundreds of healthy whales swim as one onto the same fatal beaches and refuse to leave, even after rescuers drag them back to sea. Decades of science have offered sonar, solar storms, sick leaders and treacherous sand. Not one of them fully explains why the pods keep dying together.

For a few nights in April 2005, more than a thousand toads in a quiet Hamburg pond swelled to bursting and detonated, flinging their entrails a full metre across the water. A Berlin vet named a culprit nobody had imagined. The official file still reads: no satisfactory explanation.

At daybreak on 14 April 1561, the citizens of a great German city looked up and saw spheres, crosses and blood-red globes wheeling in combat above their rooftops. A single printed sheet preserved the account. Nearly five centuries later, we still argue about what they saw.

They last a thousandth of a second, blaze brighter than whole galaxies, and arrive from billions of light-years away. For years astronomers were not even sure they were real. We now know fast radio bursts exist, and one of the hardest questions in modern astronomy is what on earth is making them.

It came from another star, tumbled like nothing we had ever seen, and accelerated without a trace of exhaust. Scientists still argue about what slipped through our solar system in 2017.

He was found dead against a seawall on an Adelaide beach in 1948, his clothing stripped of every label, a scrap of Persian poetry reading it is ended sewn into a hidden pocket. For seventy-four years he had no name, only a code no one could break and a phone number no one could explain. Then DNA offered an answer, and somehow the mystery only deepened.

A distant star kept losing up to a fifth of its light in ragged, unpredictable dips. No planet could do that. For a while, even serious scientists whispered about alien engineering.

At harvest time in twelfth-century Suffolk, reapers found two children with green-tinted skin, crouched by a wolf pit, speaking no tongue anyone could name. Two monks, decades apart, wrote it down as fact. Eight hundred years later, historians still cannot agree whether it happened, what it means, or where the children came from.

On 13 October 1917, an enormous crowd at Fátima, Portugal, reported seeing the sun spin and plunge toward the earth. Even an anticlerical newspaper printed it. No observatory on the planet recorded a thing.

A magazine writer drew a triangle on the Atlantic in 1964. It took one librarian and two insurance ledgers to erase it.

For over a century, glowing orbs have danced across a Texas desert basin. Physicists traced most of them to a highway. Most — not all.

After heavy snow in 1855, a single line of hoof-like prints was said to run for scores of miles across Devon, over rooftops and haystacks. The deepest mystery may be the record itself.