Tiny crab robots are so small they can walk on top of a US penny

This is the world's smallest remote-controlled walking robot, developed by researchers at Northwestern University.
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(CNN)Sometimes, hope is hard to find.

Yet at its most elusive, hope still resides within the human spirit -- a force that is capable of growth and change.
It's the same perpetual motion that has propelled innovation on our planet for thousands of years and made the impossible possible.
    Just this week, scientists shared that they were able to gene-edit tomatoes to provide a new source of vitamin D, vital in keeping our bones, muscles and teeth healthy.
      And researchers studying the moon found ice sheets from ancient volcanoes that could one day be used by astronauts for drinking water and rocket fuel.
      It's inspiring to think of what we're capable of when we work together, and "we all shine on, like the moon and the stars and the sun."

      Trailblazers

        A tiny robotic crab stands on the edge of a US penny.
        If you tried to play a game of "I Spy" with these robots, you might lose.
        The world's smallest remote-controlled walking robots are more miniscule than the thickness of a United States penny.
        Engineers at Northwestern University created the tiny robots, which resemble crabs, inchworms and crickets. Made from shape-memory alloy, the robots start out as flat as a piece of paper. Heat from lasers allow the robots to come to life and move around.
        These little critter bots are still in development, but the researchers envision a future that could include minimally invasive surgeries or even flight.

        Dino-mite!

        Dinosaurs like the towering T. rex and lumbering Brachiosaurus were hot-blooded (and scientists checked it to see).
        Early on, paleontologists grouped dinosaurs with reptiles, which are cold-blooded. But modern researchers have come to the consensus that dinos were much more like birds.
        Now, a groundbreaking study has found some dinosaurs were warm-blooded like birds and mammals. So what's the difference? Warm-blooded animals require lots of oxygen and calories to maintain their body temperature, while cold-blooded animals breathe and eat less.
        The researchers also revealed that other dinosaurs like Triceratops and Stegosaurus evolved to be more like cold-blooded animals -- and that could change the way we understand their evolution.

        A long time ago

        This is Burnswark Hill fort in southwest Scotland, where Roman legions tried to push their boundary northward.