A developing embryo repeatedly divides without growing, so each new cell inherits less room. Does the machinery of mitosis simply shrink with it? New work in C. elegans embryos found a striking split. The mitotic spindle—the microtubule machine that organizes division—became shorter as cells became smaller. But the dynamics of chromosome separation remained largely unchanged. Imaging, laser ablation, electron tomography, and modeling point to different physical modules: astral microtubules and cortical motors tune spindle elongation to cell size, while microtubules in the spindle midzone help preserve chromosome movement. Development often preserves an outcome without preserving every dimension of the machinery. Robustness can come from letting different parts of a system follow different scaling rules. Open-access paper: doi.org/10.1038/s41467-026-7…