Answer:
Big as a saucepan, deep as a cup, Even a river can't fill it up. What is it
Prior to smartphones, people used this to record their lives.
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They come out at night without being called, and are lost in the day without being stolen. What are they?
What can get you there in eco style, pushed by your legs mile after mile?
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?