The Shadowers (creatures)

The Shadowers are flying creatures that eat the past timeline. They are worm like creatures that have gaping mouths filled with teeth which they use for devouring the past timeline.

Codys Dads discription
Codys dad either somehow knew about the shadowers or time just used his imaginary nightmares to clean up whats left of the past. How codys dad described them though was that they only lurk in the dark. According to the movie when morty and cody go into the 23 minutes ago timeline they hear the shadowers in the mountains across the ocean. The sounds got louder as the sun started setting. But in the 12 minutes ago timeline the shadowers came out of the ocean in daytime, meaning they somehow faced their fear of light.

History
Shadowers are flying worm creatures with gaping mouths filled with teeth. They're the only organisms with the power to time travel. They do NOT go in the present time no matter what. Because anything coming from the past into the current timeline will cause a blackhole which will devour the entire universe, and all timelines of history, you wouldn't be reading this if even one shadower entered the current timeline.

Organic Food
Shadowers have only eaten one live person, and thats cody.