Cyanobacteria, otherwise known as blue-green algae, are single-celled organisms that scientists have long known to have an ability to move toward or away from light. But new research suggests this ability is even more advanced than was ever believed possible for such simple life forms.

It turns out, cyanobacteria can actually "see" the world around them, at least in rudimentary fashion, reports NBC News.

These organisms may only be single-celled, but they're spherical shaped like an eyeball — and that's apparently no accident. Each cyanobacteria has the ability to focus just like a human eye does, though the resultant image is a bit blurrier.

"Spherical cyanobacteria are probably the world's smallest and oldest example of a camera eye," wrote Conrad Mullineaux and colleagues of the University of Freiburg in Germany and Queen Mary University of London.

"Our observation that bacteria are optical objects is pretty obvious with hindsight, but we never thought of it until we saw it," Mullineaux said. "And no one else noticed it before either, despite the fact that scientists have been looking at bacteria under microscopes for the last 340 years."

This ability is particularly handy for cyanobacteria because these organisms use photosynthesis just like plants do. In other words, figuring out how to best absorb light is essential to their lifestyle.

The team made the discovery by exposing the organisms to laser light while observing their behavior under the microscope. They found that the cyanobacteria are extremely discriminating, able to find just the right amount of light that sustains life without burning them.

It's possible that other spherical bacteria have this ability too, though more research will be needed to see just how extensive this sense of sight is among single-celled organisms.

"The idea that bacteria can see their world in basically the same way that we do is pretty exciting," said Mullineaux.

Of course, having the ability to see and respond to that sensory input is different from the ability to form a conscious impression of what is being seen. There's no reason to think that these bacteria have optical experiences of the world around them like we do. Even so, it's a remarkable discovery, and it proves that the origins of optics in biology may go back far further than previously thought.