Typical organic life is soft and fluid, regenerating itself and re-organizing its forms to cope with change and the directionality of living energy flows, at least until a given system iteration slides into decline and dies as a whole, its constituents dissolving into chaos until they are picked up again by another ascendant living system. And this reorganization and regeneration can typically be achieved by drawing resources from the near ambient environment, freely, by the living systems with the will and ability to do so.
But the harder and more inert something gets, which can be applied self-consciously by a living system to better fix and perpetuate itself, the more organized energy is needed to reshape it.
Metals and buildings for instance- which persist for longer spans of time and allow for more further tiers of complexity - don't "heal" when they are left alone. They consist of definite shapes which instantly become dysfunctional when broken or misshapen past a certain point, and the methods for restoring these things are so scarce, specific, and concentrated within a given intelligence, that they can easily be taken dominion over and controlled in space and time.
