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[00:00.40] Nasa's Perseverance Rover has spent the past four years exploring an area of Mars called the Jezero Crater.

[00:08.90] It's dry and dusty, but billions of years ago, it was thought to be an ancient lake with a river flowing into it.

[00:13.41] The intriguing rocks were found on the riverbed.

[00:16.34] They have unusual ringed markings, nicknamed 'leopard spots' by the researchers, and black dots the team are calling 'poppy seeds'. These features are actually minerals, and the scientists think they could have been produced by chemical reactions associated with microbes.

[00:31.48] Life isn't the only possible explanation.

[00:34.66] The minerals could have been made by natural geological processes.

[00:39.45] The only way to find out for sure is to bring the rocks back to Earth for analysis.

[00:42.90] Missions to return samples have been proposed, but there's uncertainty because of the proposed cuts to Nasa's budget.

[00:49.80] While there's still much to find out, these rocks are tantalising, and the findings are strong enough to meet Nasa's criteria for potential biosignatures, features that warrant further investigation to determine if they really are a sign of life.