While the James Webb Space Telescope observed the atmosphere of an alien world 120 light-years away, it picked up hints of a substance only made by living things — at least, that is, on Earth.
This molecule, known as dimethyl sulfide, is primarily produced by phytoplankton, microscopic plant-like organisms in salty seas as well as freshwater.
tl;dr "only made by" is not the same as "primarily produced by." The molecule in question is only made by living things on Earth.
Scientists involved in the research caution that the evidence supporting the presence of dimethyl sulfide — DMS, for short — is tenuous and "requires further validation," according to a Space Telescope Science Institute statement.