Cyclic di‐GMP signaling regulates sessile‐to‐motile lifestyle transition and associated physiological and metabolic features in bacteria. The presence of potential cyclic di‐GMP turnover proteins in deepest branching bacteria indicates that cyclic di‐GMP is an ancient signaling molecule. In this issue of The EMBO Journal, Caiet al(2023) describe light‐induced activation of a thiosulfate oxidation pathway in the deep‐sea cold‐seep bacteriumQipengyuania flava, thus coupling cyclic di‐GMP with the regulation of the global abiotic sulfur cycle.