How come Kane did not feel that he had this rather large organism growing inside him?
Kane did not feel well and he was very hungry when he emerged from the coma the facehugger kept him under. It is unbelievable to think that the alien grew inside him as a fetus does, that is, as an independent organism feeding on the nutrients of the mother (father in this case?) More likely is the alien growing like a tumor– replacing organic matter with foreign cells, like a cancer. When the alien bursts, it seems to come out of Kane’s ribcage, which suggests it was either gestating in his stomach and somehow chose the most difficult path to escape its host (through the rib cage) or it was actually grown as a giant tumor in his lung. People have been known to have volleyball size tumors in their abdomen or chest and not be aware of it. This alien would be a tumor that grew especially fast, with an extremely rapid metabolism.
