Here's why:
* Verb: The base form of the word is "creep", which means to move slowly and quietly.
* Past Participle: "Crept" is used in the past perfect tense ("had crept") and the present perfect tense ("has crept"). It can also be used as an adjective to describe something that has moved slowly and quietly.
Examples:
* Past Perfect: He had crept into the room without making a sound.
* Present Perfect: The cat has crept under the bed.
* Adjective: The crept shadow moved across the wall.