After scooping up a bit of Martian soil, rover engineers noticed a bright object on the ground. Speculation is it's a piece of metal or plastic that fell from the rover. Click here for a larger image.
Mars Science Laboratory: Images: "This image from the right Mast Camera (Mastcam) of NASA's Mars rover Curiosity shows a scoop full of sand and dust lifted by the rover's first use of the scoop on its robotic arm. In the foreground, near the bottom of the image, a bright object is visible on the ground. The object might be a piece of rover hardware. This image was taken during the mission's 61st Martian day, or sol (Oct. 7, 2012), the same sol as the first scooping. After examining Sol 61 imaging, the rover team decided to refrain from using the arm on Sol 62 (Oct. 8). Instead, the rover was instructed to acquire additional imaging of the bright object, on Sol 62, to aid the team in assessing possible impact, if any, to sampling activities.
For scale, the scoop is 1.8 inches (4.5 centimeters) wide, 2.8 inches (7 centimeters) long"