Complex sentence: Marlow's wife was attacked by a facehugger, and seeking help, Marlow brought her aboard Sevastopol for treatment, and the Alien hatched from her and began to wreak havoc on board.
Split into simpler sentences: Marlow's wife was attacked by a facehugger, and seeking help, Marlow brought her aboard Sevastopol for treatment. Then the Alien hatched from her and began to wreak havoc on board.