Mars had an oxygen-rich atmosphere around 4 billion years ago
13
Cows can sleep standing up, but they can only dream lying down.
745
There is a mass reservoir of water floating in space that is 100,000 times bigger than our sun and holds 140 trillion times more water than all of our oceans.
11
The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13
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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