Researchers at the NanoRobotics Laboratory of the École Polytechnique de Montréal, under Professor Sylvain Martel, produced this remarkable video showing a swarm of about 5,000 flagellated bacteria–of a type which are subject to manipulation by magnetic fields–being directed to assemble six 100 μm epoxy bricks into the shape of a tiny step pyramid. IEEE Spectrum explains:

The bacteria, of a type known as magnetotactic, contain structures called magnetosomes, which function as a compass. In the presence of a magnetic field, the magnetosomes induce a torque on the bacteria, making them swim according to the direction of the field. Place a magnetic field pointing right and the bacteria will move right. Switch the field to point left and the bacteria will follow suit.

The corresponding paper title is surely one of the best I’ve ever read: “A Robotic Micro-Assembly Process Inspired By the Construction of the Ancient Pyramids and Relying on Several Thousands of Flagellated Bacteria Acting as Workers.” [Thanks, Glen!]