Here's one for you folks who don't have enough head-scratching moments of your own...
According to a story in Boing Boing, a resident of Vladivostok, Russia was tossing coal into a stove when he noticed a bit of metal embedded in a lump of coal. He took the lump to officials in the area, and they had it examined by scientists at the St. Petersburg Institute of Nuclear Physics where it was determined to be about 300 millions years old.
The problem with that age determination is that the aluminum piece in question looks very man-made, almost precise in the manner of a metal rail often used in large microscopes and some electronic devices. The metal itself was determined to be aluminum with about 2% magnesium, a composition matching the elemental mix often found in meteorites.
So is this some extra-terrestrial piece of space junk that's found its way into a 300 year old lump of coal in Russia? Or is it evidence of a previously unknown civilization that pre-dates all known human life?
According to this article, this sort of discovery is far from unique:
Nowadays, finding a strange artifact in coal is a relatively frequent occurrence. The first discovery of this sort was made in 1851 when the workers in one of the Massachusetts mines extracted a zinc silver-incrusted vase from a block of unmined coal which dated all the way back to the Cambrian era which was approximately 500 million years ago. Sixty one years later, American scientists from Oklahoma discovered an iron pot which was pressed into a piece of coal aged 312 million years old. Then, in 1974, an aluminum assembly part of unknown origin was found in a sandstone quarry in Romania. Reminiscent of a hammer or a support leg of a spacecraft “Apollo”, the piece dated back to the Jurassic era and could not have been manufactured by a human. All of these discoveries not only puzzled the experts but also undermined the most fundamental doctrines of modern science.