During an extended post-meiotic process of mammalian sperm differentiation (spermiogenesis), mammalian sperm alter their mitochondria pool in two ways: excess mitochondria are segregated to the residual body, whereas the rest are remodelled and reorganized around the flagella5. During nematode spermatogenesis, residual bodies form immediately after anaphase II, but the mitochondria segregate exclusively to the sperm6. How nematode sperm regulate mitochondrial quality and numbers has been unknown. In this issue of Nature Cell Biology, Liu, Shi, Sheng et al.7 applied several cell manipulation and imaging technologies to the analysis of C. elegans spermatogenesis. Using these approaches, they discovered another mechanism by which cells can expel excess mitochondria, showing that C. elegans sperm expel nearly one-third of their healthy mitochondria by budding individual mitochondria directly from their plasma membrane (Fig. 1).