https://en.wikipedia.org/wiki/The_Thing_(1982_film)

one

  • Founders - Change shape
  • Thing - Change shape

two

  • Founders - live in a giant soup and can split off from the soup at will
  • Thing - Can divide up the shape at any time into autonomous functional groups

three

  • Founders - Fly in space ships
  • Thing - Flies in massive space ship

four

  • Thing - Doesn’t like fire
  • Founders - who likes fire?

I posit that the founders are the Thing, but perhaps a group of founders operating in special operations mode. Or they could be children out on founder Rumspringa like Odo was.