If a robot is made of living cells, can respond to external stimuli and has the ability to compute and coordinate movement, is it alive?

This question can be posed of a new, tiny stingray-inspired robot that is able to follow pulses of light to swim through an obstacle course.

“It’s not an organism per se, but it’s certainly alive,” said Kevin Kit Parker, a professor of bioengineering at Harvard University and one of the authors of a paper detailing the robot, published in Science on Thursday.

To create the robot, which measures 16 millimeters in length, Dr. Parker’s team layered heart cells from rats onto a gold and silicone scaffold that they designed to resemble a stingray. They then injected a gene into the cells that caused them to contract when exposed to blue light.