Nasa's Curiosity rover has found a ball on the surface of Mars. The Mastcam on Curiosity snapped the spherical object sitting on a flat rock on the Red Planet.

mars ball
Have the Martians been practising for the Ryder Cup? A camera on Nasa's Curiosity rover photographed a spherical rock on the surface of the red planet NASA/JPL-Caltech/MSSS

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

The rover also took a photo of what looks like a set of traffic lights protruding from the ground.

mars traffic lights
Traffic lights on Mars, as captured by Nasa's Curiosity rover Nasa/JPL-Caltech/MSSS

Over the years, conspiracy theorists and bloggers with over-active imaginations have spotted all sorts of things on the Red Planet, including a fossilised dinosaur thigh bone, a military helmet, several rats and an iguana.

These are all examples of Pareidolia, the psychological need to see significance in random data, such as seeing faces in clouds.