Some bacteria genetically control the biomineralisation of intracellular amorphous calcium carbonates (iACC) with potential implications for microbial physiology, evolution, bioremediation and biogeochemical cycling. Until now, this capacity has been documented in Cyanobacteria , the giant gammaproteobacterium Achromatium and a few magnetotactic Pseudomonadota and Nitrospirota . Here, we report the discovery of iACC biomineral...