One could, in principle, imagine “creatures” that are far larger. If we draw on Landauer’s principle describing the minimum energy for computation, and if we assume that the energy resources of an ultra-massive, ultra-slothful, multi-cellular organism are devoted only to slowly reproducing its cells, we find that problems of mechanical support outstrip heat transport as the ultimate limiting factor to growth. At these scales, though, it becomes unclear what such a creature would do, or how it might have evolved.