This ability functions much like normal sight, except that instead of seeing light, a creature with lifesense sees life. Life sources glow much like light sources with the average Small, Medium, or Large living creature giving out “light” like a torch, which gives bright “illumination” out to 20 feet and shadowy “illumination” out to 40 feet. This life-illumination reveals things around it exactly as a normal light source would, except that it is not blocked or suppressed by darkness or magical darkness.
In the absence of a living creature, a creature cannot use lifesense to detect anything around them, no matter how bright the normal light may be. A living creature with this ability can see using their own life-illumination.