What appears to be a book has been photographed on the Martian surface by researchers / bloggers at Mars Moon Space Zoom Club
The anomaly, photographed in the Gusev Crater, an ancient lake bed filled with sediments, was formed roughly 4 billion years ago.
The possibility of it being artificial / Intelligently made, are strong.
Had it been photographed on Earth there would be no question that is an Old Book. But this is Mars, it can't possibly be a Book - or could it ?