Simile

A figure of speech that makes a comparison between two unlike things and uses the words "like," "as," "than," or "resembles."

Example From Text

There was no warning, only a leap in like a flash, a metallic clip of teeth, a leap out equally swift, and Curly's face was ripped open from eye to jaw.

Explanation

London compares the movements of the husky dog with a flash to emphasize how quickly and suddenly he attacked Curly. A flash is something so quick you almost can't see it.