This miniature choo-choo train was discovered rolling down the tracks on a LeCroy MVV 200 analog shift register integrated circuit. The "tracks" upon which the train is apparently riding are the high speed shift register.
"No purchase necessary", "Keep away from fire", and "not for resale" are clearly visible in the magnified portion shown as an inset within the photomicrograph. The pad containing this warranty is 450 microns tall by 1850 microns wide and sports 25 lines of text, with each character being between six and eight microns high. This disclaimer--probably the smallest ever written--was found on a Hewlett-Packard "Aspen" (Acquisition Signal Processing ENgine) chip used in digital oscilloscopes in the late 1980s and early 1990s.