A mysterious circular object the size of a jumbo jet has been discovered on the floor of the Baltic Sea. Professional shipwreck hunters identified the anomaly, and a smaller circular object, while searching with sonar.

Experts have identified the precise location in Wales of some of the megaliths used in the construction of Stonehenge.

It’s a pretty major achievement to discover the location of the millennia-old quarry down to a few metres, but this also throws up some new mysteries. The rhyolitic rocks differ from all others in South Wales. The presumption is that they were chosen for a specific reason. How were they identified and why? There has been some interesting work done elsewhere into the acoustic qualities of particular stones at prehistoric sites. Is this important?

And this discovery has also kicked a hole in theories of how the stones were transplanted to Salisbury Plain. A consensus was growing that they were floated on rafts along the coast, but the exact location’s inaccessibility to water makes this unlikely. The old geologic theory – that the stones were pushed by advancing glaciers from Wales to Wiltshire during the ice age – is pretty flimsy as there aren’t any other Welsh rocks scattered around the Plain.

This new look at an old discovery is raising questions about whether ancient aboriginal culture had a deep understanding of the movement of the stars.

“They have discovered that waist-high boulders at the tip of the egg-shaped point along the ring to the position on the horizon where the sun sets at the summer and winter solstice – the longest and shortest day of the year.”

Anyone who’s read The Scar-Crow Men knows that codes play an important part in the story, as they did for real spies in the sixteenth century…and today.

New Scientist has a great article this week on eight codes that still remain unbroken, from the famous Voynich Manuscript to the CIA’s Kryptos monument to one of the final messages from the Zodiac serial killer.

Worth a read. You’ll have to sign up, for free, but you only get a window of a couple of days to check it out.

Symbols and numerals have been discovered hidden in the eyes of Da Vinci’s Mona Lisa after clues were found in a half-century old book.

“We are only at the start of this investigation and we hope to be able to dig deeper into this mystery and reveal further details as soon as possible. It’s remarkable that no-one has noticed these symbols before and from the preliminary investigations we have carried out we are confident they are not a mistake and were put there by the artist.”