A Harvard University professor, Kevin Kit Parker, has produced a robotic stingray.
The robot is made of an elastomer body, a gold skeleton and a muscle layer made from artificial rat heart cells.
The rat heart cells have been genetically engineered to react to light.
The robotic stingray swims in a mixture of glucose, warm water and salt. This mixture provides the cells with energy.
Artificial creations like this could help pave the best way to create a human heart.