NASA's Mars rover Curiosity has dug up a mini-mystery for scientists: an odd white fleck that sticks out like a beacon in the reddish soil.

It looks out of place, but scientists say that it's probably just a different hued bit of Martian soil.

It's only 1 millimeter in size and was spotted after the rover used its mechanical scoop to dig up some dust.

Project scientist John Grotzinger says researchers first thought it was earthly contamination from Curiosity. But it's likely natural Martian soil that looks different because of the way it's angled in the light or how the soil broke apart. Or it could be made of different minerals.

Curiosity will use its camera and instruments to try to learn more about what it is.