The Intruder Within

Everett is a "tool-pusher" on an oil rig for the Zorton Oil Company, who drills to 19,000 feet to uncover a hideous creature from our ecological past, a spawn that implants reproductive sperm within a human being. When that man goes crazy and attacks a woman crew member, she is destined to give birth to... you know what, don't you? The monster passes through evolutionary stages before becoming a man in a glistening fright suit. (John Stanley's Creature Features Movie Guide Strikes Again)