Mars Rover Discovers Book-Shaped Rock on Red Planet
NASA's Curiosity Mars rover captured a close-up view of a rock nicknamed "Terra Firme" last month, which looks like the open pages of a book. The rock is about an inch across and was snapped by the rover's Mars Hand Lens Imager. Rocks with unusual shapes are common on Mars and often were formed by water seeping through cracks in a rock in the ancient past, bringing harder minerals along with them.

