Thermoses
Thermoses were originally created to keep chemicals at a stable temperature. A scientist placed one glass bottle inside of a larger one and then evacuated the air between them. Today, they're used to keep drinks hot or cold for hours.
Paper Clips
When people submitted designs for paper clips, they came up with all different kinds of crazy shapes. The paper clip as we know it today doesn't damage the papers and is easily able to bind papers without seeming cumbersome. The current straightforward design won out over all the rest.