Archelon is a prehistoric sea-turtle from the late-cretaceous period of North America, around seventy-six-million-years ago.
Archelon looks like a living sea-turtle, but is much larger than any species today, about the size of a car. It also had a beak shaped more like a hawk than a turtle, suggesting it was more predatory.
In the film
An Archelon was briefly seen in Pero Pero's flashback.