We unexpectedly found this very Princetonian creature while doing a scanning electron microscopy lab in MSE 302, Laboratory Techniques in Materials Science and Engineering.

In this particular experiment, we were studying the effects of cooling rate on the structures and properties in low carbon steels. One of the important effects is a change in the microstructure which can be observed by appropriate sample preparation and microscopy. The expected structure upon slow cooling from high temperature to room temperature features randomly oriented regions or "grains" of striped materials known as pearlite and regions of smooth material known as ferrite. The coarseness and size of these grains depend primarily on the amount of carbon and the rate at which the sample is cooled.

In the center of the image (magnified by ~5500 times) one sees a particular grain of pearlite that happens to be in a shape resembling a proud tiger. The tiger is approximately 10 microns long and 5 microns tall at the shoulder, or about 1/10 the width of a human hair.