As in Roswell, New Mexico.
Ironically, EGS-canon is that it actually was a weather balloon in Roswell back in the day.
It's just there also happen to be actual aliens out there (regardless of where Uryuoms may or may not be from), and flying mysterious monstrosities that resemble turtles.
It's funny how things work out.
I needed a reason for Mr. Verres to leave, which started out as a "ha ha, Gamera reference" joke. Now I have a design in mind for "the monstrosity", and actually know what it wants to talk to Mr. Verres about.
That's what happens when I try to intentionally make jokes that were never intended to be explained. I think up explanations for them.