Plays a role in maintaining mitochondrial morphology (PubMed:21248201). May act as a component of the MICOS complex, a large protein complex of the mitochondria (By similarity). Component of the mitochondrial contact site and cristae organizing system (MICOS) complex. Abnormal mitochondrial morphology with localized swellings and tubular extensions. Double knockout with moma-1 or immt-1 results in reduced or no brood, poor growth and withered gonads. Furthermore, in double knockouts with moma-1, the gonads contain fewer mitochondria. Belongs to the MICOS complex subunit Mic19 family. Metazoan Mic19 subfamily.