Percy Fawcett set out to solve a mystery and only compounded it. In 1925, after studying ancient legends, the British archaeologist became convinced that the dense Matto Grosso region of western Brazil concealed a lost city that he called “Z.” In May he set out with two other men into the uncharted jungle, leaving a note that none should try to rescue them if they did not return.

They didn’t. The decades that followed brought many rumors: Fawcett had been murdered by Indians, killed by a wild animal, stricken with amnesia or felled by illness. In all, 100 rescuers in 13 expeditions have died trying to discover what happened to him. To this day, no one knows.

Mr. James Wrigley, master of the Golden Lion inn, at Liverpool, going into his cellar, October 26, 1759, having some oysters there, a large Norway rat, endeavouring to seize an oyster that was open, it closed, and held him so fast, that he was carried into the kitchen, and exhibited to some hundred persons, while alive.

— Annual Register, 1759

Daniel McCartney never needed a diary — he could remember every day of his life since age 9. On his death in 1887, the Cardington, Ohio, Independent published this account:

That the reader may more clearly understand what has just been written, I will give Mr. McCartney’s answer to a question of my own: ‘Wife and I were married on the 28th day of January, 1836; give the day of the week, the kind of weather, etc.?’ He gave answer in a few seconds. ‘You were married on Thursday, there was snow on the ground, good sleighing and not very cold; father and I were hauling hay; a sole came off the sled, we had to throw the hay off, put a new sole on the sled and load up again before we could go.’

The writer (whose name is not given) met McCartney again a dozen years later and asked the same question. McCartney gave the same details.

March 15, 1761, Tregoney, in Cornwall. As some tinners were lately employed on a new mine, one of them accidentally struck his pick-axe on a stone. The earth being removed, a coffin was found. On removing the lid they discovered a skeleton of a man of gigantic size, which, on the admission of the air, mouldered into dust. One entire tooth remained whole, which was two inches and a half long, and thick in proportion. The length of the coffin was eleven feet three inches, and depth three feet nine inches.

— Annual Register, 1761

On Jan. 31, 1921, the five-masted commercial schooner Carroll A. Deering was found aground in North Carolina. The ship’s log, navigation equipment and lifeboats were missing, as were the crew’s personal effects. She had last been sighted by a lightship at Cape Lookout, whose captain had spoken with a thin man with reddish hair and a foreign accent — decidedly not the Deering‘s captain. The lightship also noted that the crew seemed to be “milling around” on the Deering‘s foredeck, where they were usually not allowed.

But that’s all anyone knows, really. The crew’s disappearance remains unexplained to this day. Was it piracy? Mutiny? A commandeering by Russian communists? Without evidence, it remains a mystery.

The Wolfsegg Iron is a lump of iron found inside a block of coal at a mine in the Austrian village of Wolfsegg. The scientific journal Nature describes it as “almost a cube” with a “deep incision” running around it. It weighs about 1.7 pounds.

It’s not at all clear where it can have come from. A meteorite would not have such an artificially cubical shape, and prehistoric civilizations should not have had the technology to make such a thing.

After a thorough examination in 1966, researchers at Vienna’s Natural History Museum concluded that the block is simply man-made cast iron, perhaps used as ballast in primitive mining machinery. But no other such blocks have ever been found.