The strangers in your dreams are actually people that you've seen in real life.
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Mars had an oxygen-rich atmosphere around 4 billion years ago
13
Scientists have revived a flowering plant from a fruit stored away in permafrost by Arctic ground squirrel 32,000 years ago.
16
The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13