It is in fact, none other than that famous mathematical constant Pi. The image is a "walk" made out of the first 100 billion digits of pi, in base 4.
The mystery object is, in fact, the asteroid Toutatis. It was snapped last week by China's Chang'e 2 probe when it flew by the lump of rock. The three-mile-long asteroid was 4.4 million miles from Earth when Chang'e 2 passed it by, missing the tumbling rock by just 2 miles.