Several mysterious symbols have been sent to us from around the world, and after a bit of investigation by some of our expert referees, we've managed to find plausible explanation for most.
But there are a few which haven't been met with a satisfactory explanation - hence this series. If you have any ideas about any of the symbols below, please let us know.
Here are a few of tests to fire-up your brain cells.
...and of course, any of these symbols could have no meaning at all - merely the results of somebody's doodling. But if you fancy a challenge, click on a link above for more details.
Happy sleuthing!