Salps are jelly-like sea creatures, so humble that few people even know they exist. But there are countless numbers of them swimming in the world’s oceans and they help fight climate change. Salps cruise around the sea surface at night, sucking up and digesting phytoplankton, microscopic plant-like organisms that absorb CO2 for their photosynthesis. During the day, the salps sink deeper in the sea, possibly to avoid predators, and squirt out unusually heavy droppings rich in carbon left over from their phytoplankton meals. The pellets sink rapidly, up to 1,000 metres deep in a day, and faster than the pellets of most other sea creatures. And when the salp dies, its body also sinks rapidly, sending even more carbon to the ocean depths. According to a study published last year, salps, jellyfish and other gelatinous creatures such as comb jellies remove up to an estimated 6.8bn tonnes of carbon each year from seas around the world. Of that, some 2bn tonnes of the carbon is thought to fall to the seafloor where it stays locked up and out of harm’s way. Salps remain largely unappreciated, but they are powerhouses in curbing climate change.