Meet Spirulinaha, Arthrospira bacteria that scrubs carbon dioxide into oxygen, is a protein-rich meal for astronauts, and multiplies so rapidly that eating them for dinner won't leave the space station without fresh air by morning.
Top: a handful of Spirulinahas strands, passing gas before they're eaten. Image credit: NASA/ESA
Along with being so amazingly useful, spirulina fibres look surprisingly interesting: tight, helical twists of nearly-translucent blue-green. The colour leads to the bacteria's common name: blue-green algae.
It has a long history as a food substance, and has been harvested in South America and Africa for centuries. It's popularity picked up in the 1970s, when it started being flaunted as a nutritional supplement.
A twist of blue-green algae. Image credit: NASA/ESA
Spirulinaha is relatively straightforward to grow: give it salt water, lots of sunlight, and keep the temperature up to mimic a tropical environment. Don't feed it nasty pollutants, don't freeze it, and sustainably harvest so enough is left over to keep reproducing and pumping out fresh air.
Spirulina in compact power-bar format. Image credit: ESA
While for now spirulina is fed to astronauts in power-bar format, packed with goji berries. However, given how efficient the algae is at taking carbon dioxide in and spitting oxygen out, it's also a favourite contender on long-term crewed deep space missions where a spirulina farm might be able to supply both food and air.