This innocent looking brick has been "biomanufactured" by mixing sand with a solution of bacteria that we've been promised is non-toxic and non-pathogenic, and if every brick in the world was made this way, it would spare the atmosphere of some 800 million tons of CO2 every year.
Bricks are a fairly ubiquitous building material because they're as cheap as dirt, they're easy to make out of locally sourced materials, and they last a long time. Problem is, every single brick that's produced ends up adding an average of 1.4 pounds of CO2 to the atmosphere, due mostly to the fact that curing bricks requires heating in kilns that are usually fired with coal.
Ginger Krieg Dosier, a professor of architecture at the American University of Sharjah in Abu Dhabi, has come up with a better way to make bricks that doesn't involve any heat at all: bacteria. A bacterial "cementing solution" can be mixed with sand, which causes the sand to precipitate calcite, binding everything together into sandstone over a period of about a week. It's easy, it's cheap, you don't even need a kiln, and as long as you're comfortable going to sleep every night surrounded by a ton or two of microscopic dead bugs, it's just as good as the real thing.
If you like the idea of making stuff out of bacteria but don't feel the need to live inside their remains, this same technology can also be used in rapid prototyping machines and 3D printers like the one above.