හවුල් ශ්‍රව්‍ය

As the viper moves closer, tiny sensors on its face pick up the heat released by warm-blooded animals. That warmth activates a paper-thin membrane inside, causing the snake's brain to transform the signal into a thermal image. This lets it spot the animal in darkness before it attacks, and it works so brilliantly that scientists even built a camera from the very same concept, turning unseen heat into a clear visible picture.