US scientists have found further evidence that huge seas existed long ago on Mars.

A geological mapping project found sedimentary deposits in a region called Hellas Planitia which suggest a large sea once stood there....

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The book's still out on there being water now. Even underground aquifiers.

This basin had water between 4.5 and 3.5 billion years ago. Oldest life on earth is about 3.3 billion years. Still not beyond reasonable doubt that life started on Mars and hitch hiked over to Earth on an asteroid. In which case we are all Martians.