A new biological “robot” changes color as it moves and could help researchers test out drugs—but, no, it doesn’t fly.

What’s your bioinspiration? Scientists led by Fanfan Fu, at the bio-electronics lab at Southeast University in Nanjing, China, wanted to mimic the iridescent, color-shifting properties of chameleon skin. Their result is this new bio-bot.

How it works: The team molded a butterfly shape out of gel and then added iridescent nanocrystals. After that, they added a layer of heart cells taken from a rat. When the heart cells beat, the nanoparticles get stretched and change color, creating the impression of flying wings.

Why it’s useful: Fu says that the light changes could serve as a simple display in heart-on-a-chip experiments. Researchers could, for instance, observe the rate of color change when they give the bio-robots a heart-rate-lowering drug.