Mitochondria

Mitochondria are ancient bacterial invaders that became so essential you cannot imagine life without them. Between 1.5 and 2 billion years ago, an ancestral cell engulfed a bacterium capable of aerobic respiration. Instead of digesting it, the cell kept it alive. Over evolutionary time, the bacterium lost genes for independent survival while the host became dependent on the bacterium's energy production. This is endosymbiosis - the permanent merger of separate organisms.

Right now, in every cell of your body except red blood cells, dozens to thousands of mitochondria are burning oxygen to produce ATP. They have their own DNA (inherited only from your mother), their own reproduction cycle, their own double membrane marking their bacterial ancestry. They're technically separate organisms that became so integrated into your biology that their independence is unrecognizable. Every breath you take feeds these ancient invaders.

For business, mitochondria illustrate that the most successful partnerships aren't alliances - they're absorptions so complete that separation becomes impossible. The strongest competitive advantages come not from what you own but from what has become physiologically integrated into your operations. Companies acquiring capabilities often maintain separation ('strategic autonomy'), but mitochondria teach that true competitive advantage requires digestion: taking external capabilities and integrating them so deeply that they become indistinguishable from your core functions. The question isn't 'build or buy' - it's whether you're willing to genuinely metabolize what you acquire.