The official (per Guinness World Records) world’s smallest stop-motion movie is this one, created by a research group at IBM by moving atoms under a really powerful microscope.
“A Boy and His Atom” uses stop-motion animation to show a figure dancing, jumping, and playing ball. It’s rudimentary, jerky, and looks like it was made with BBs, but when you realize what you’re viewing, it’s amazing. Particularly since, when exposed to a whole new way of seeing the world, these researchers decided to make a cartoon! There’s something important there to be said about the essentiality of art.
This news article about the film says it’s just under 250 frames, created on a copper surface, and magnified more than 100 million times.