CNN  —  A fish under a roof. A stick figure without a head. A series of lines that look like a garden rake. These symbols are part of an entirely undeciphered script from a sophisticated ancient civilization thousands of years old. And they remain an enduring mystery that has sparked heated debates, death threats to researchers, and cash prizes for the coveted answer. The latest such prize was offered last month by the chief minister of one Indian state: $1 million to anyone who can decode the