Mitochondria, the powerhouse of the cell, have been considered to be absolutely indispensable components of all eukaryotic cells...until now. An international team of researchers has discovered an example of an organism that has completely lost all remnants of the mitochondria. Led by Drs. Anna Karnkowska and Vladimir Hampl from Charles University, and including Lael Barlow, Emily Herman, and Joel Dacks from the Department of Cell Biology at the University of Alberta, this work overturns a fundamental principle in cell biology. This tells us both about how the mitochondria evolved and why it is so important for the functioning of nearly all eukaryotic cells today.