Premise: Gorgo is a 1961 British-American science fiction monster film directed by Eugène Lourié. The film focuses on Gorgo, an ancient large sea monster brought back to London for exploitation, and Ogra, his even larger mother, who rampages across London to search for him. The film was featured in an episode of the cult movie-mocking television show "Mystery Science Theater 3000".
Hypothesis: Gorgo is a real ancient large sea monster.