Scientists have discovered the first "living crystal" formed by a microbe—the speedy Thiovulum majus, one of the fastest swimming species of bacteria known. These bacteria live in the muddy bottoms of salt marshes and produce energy by oxidizing sulfide. Researchers discovered that when the bacteria hit the edge of a container, they move along its surface and eventually aggregate into ordered, 2D formations. The microbes generate a tornadolike flow with their spinning flagella, which pull nearby bacteria toward them, causing them to arrange in crystalline clumps, they report in a paper to be published in Physical Review Letters. Whereas most crystals are inert structures, these crystals rearrange and rotate over time, as shown in the video above, thanks to the forces each bacterium exerts on its neighbors. Scientists don't yet know if these bacteria form such crystals in their natural environment or whether there are potential applications for the result, but, says physicist Alexander Petroff of Rockefeller University in New York City, first author of the study, "it is still a great incentive to play in the mud and do math."
(Video credit: Xiao-Lun Wu)