Mars had an oxygen-rich atmosphere around 4 billion 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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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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If you have 1 billion dollars and spend $1,000 every day, it would take you 2,740 years to go broke.
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Lurch, a Watusi bull, had the largest horns in the world.
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