Spielberg hit on a simple rule of the horror movie, but quite by accident.

For the mechanical shark in Jaws was so rubbish that they simply didn't bother filming what was below the ocean.

Instead, the shark was treated as a hidden monster that strikes as if from nowhere.

Like all good horror movies, the monster wasn't truly revealed until the final act. And by then it was so scary you didn't care that it was as wooden as Elizabeth Hurley acting in a furniture store commercial.