To avoid losing a fast soccer player in the frame, a drone doesn't need a bright beacon — recognizing the silhouette is enough. Similarly, a neural network now tracks microbes: the algorithm analyzes an ordinary microscope image and instantly finds a bacterium in a drop of water. Previously, they were marked with glowing dyes, but those quickly faded, and the intense light disrupted natural behavior.
It turned out that the magnetic field serves them not as a compass, but as a depth indicator — sliding along the field lines, bacteria find water layers with the right oxygen level. Now biologists can see how a single microbe chooses its path, searches for food, and communicates with neighbors. The method reveals invisible life from soil to ocean.
Back in the 17th century, Robert Hooke examined mold under a homemade microscope but couldn't track the movement of a single bacterium. Magnetotactic bacteria contain magnetite crystals and swim along Earth's magnetic field lines — it's not a compass, but an elevator: that's how they find water layers with the right oxygen level.