Sustains mitochondrial morphology probably through maintaining cristae 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. Expressed in embryos. Abnormal mitochondrial morphology with localized swellings and tubular extensions, and distended cristae. Double knockout with fzo-1 or eat-3 RNAi results in mitochondrial fragmentation. Double knockout with chch-3 results in reduced or no brood, poor growth and withered gonads which on a cellular level contain fewer mitochondria. Belongs to the apolipoprotein O/MICOS complex subunit Mic27 family.