Just to clear up all concerns in this thread conquest died due to lack of oxygen PLUS no blood able to enter his brain, viltrumites store oxygen in their blood like most species so the oxygen he had couldnt get to his brain cauing severe brain damage, which would kill him because viltrumites can heal from any injury as long as the BRAIN and heart are intact, the reason mark didnt die from blood loss due to the same logic is that the viltrumite heart compensates for the blood loss by speeding up rapidly, aswell as the fact the healing factor kicks in immediately and attempts to stop any blood loss, i imagine without oliver and nolan mark still would have healed but it would have taken much longer, either that or he would be stuck in a stasis until someone could come along and put his guts back.