Kurtz is made of inanimate ivory...

Pg. 59-60
In this passage, Marlow witnesses the "resurrection" of Kurtz. Since Marlow has thought all along that Kurtz has been dead, it is especially shocking for him to learn that he is very much alive. As Kurtz rises from his stretcher, he is described as "the cage of a his ribs all astir, the bones of his arm waving. It was as though an animated image of death carved out of old ivory had been shaking its hand with menaces at a motionless crowd of men made of dark and glittering bronze." By being described as an "animated image of death," it shows how Kurtz was never really alive in the first place. If his alive body only resembles a moving death, then he has truly been dead all along. Also, being described as "carved out of old ivory," it proves that this obsession with the acquisition of ivory has driven him to be consumed with this passion and turn his actual body itself into a reflection of his desire. Not only has his obsession changed him, it has also killed him in a way. His once-living body has been taken and replaced for an animated corpse of ivory.