Researchers at Georgia Tech have made the ‘World’s Smallest Ad’ created for Arby’s, the fast food restaurants. 
The ad was printed on the side of a sesame seed, like the one you might find….wait for it….on a roast beef sandwich bun. The size of the ad was about 800 square microns (less than the width of a hair in either dimension) which is pretty small but still almost a billion square nanometers. If you were at the Arby’s in NYC apparently you got to ‘see’ one of these seeds using a scanning electron microscope. What happened to this seed isn’t obvious, hopefully it didn’t wind up on a roast beef sandwich that was woofed down by a customer.