Curiosity rover
A ball and a traffic light-shaped object on Mars.NASA/JPL-Caltech/MSSS

Nasa's Curiosity rover has found a ball on the surface of Mars as it travels to Mount Sharp to collect its first samples there.

Images taken with the Mastcam on Curiosity snapped the spherical object sitting on a flat rock on the surface of the Red Planet.

However, Nasa experts say the ball is not anything too exciting – saying it is probably just one centimetre wide and an example of a geological process called concretion.

mars ball
The image was taken by Curiosity on 11 September.NASA/JPL-Caltech/MSSS

This takes place when minerals separate from water and become hard masses. According to Discovery, these balls were formed during sedimentary rock formation at a time when there was lots of water on Mars.

The ball indicates that Curiosity was sitting in an ancient lakebed.

During its recent travels, the rover also took a photo of what looks like a set of traffic lights protruding from the ground, but Nasa is yet to comment on this discovery.

traffic light mars
Space video journalist estimated the 'traffic lights' to be about 30cm long.NASA/JPL-Caltech/MSSS

Spotted by video journalist Joe Smith, from Bristol, he said it is difficult to tell how big the traffic light rocks are, but probably measure about 30cm.

The findings come as Curiosity collects its first samples from Mount Sharp. The rover drilled 6.7cm into the ground to collect powdered rock samples.

Curiosity rover
The hole drilled by CuriosityNASA/JPL-Caltech/MSSS

Ashwin Vasavada, deputy project scientist for Curiosity, said: "This drilling target is at the lowest part of the base layer of the mountain, and from here we plan to examine the higher, younger layers exposed in the nearby hills.

"This first look at rocks we believe to underlie Mount Sharp is exciting because it will begin to form a picture of the environment at the time the mountain formed, and what led to its growth."