Mars had an oxygen-rich atmosphere around 4 billion years ago
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The focusing muscles of the eyes move around 100,000 times a day. To give your leg muscles the same workout, you would need to walk 80km (50 miles) every day.
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No one knows Albert Einstein's last words. Just before he passed, he spoke several words in German, but his nurse only knew English.
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The Lion's Mane Jellyfish is the largest jellyfish in the world. They have been swimming in arctic waters since before the dinosaurs (over 650 million years ago).
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The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
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