Is a cryptex a real thing?

Could you please elaborate on the authenticity of a cryptex? Many references in popular culture, particularly fiction, mention this mysterious device as a means of concealing sensitive information. However, does it actually exist in the real world? If so, what is its purpose and how does it function? Or is it merely a figment of an author's imagination, used to enhance the narrative in stories? Clarifying this point would be immensely valuable, especially for those of us fascinated by the intersection of cryptography and ancient artifacts.