Create a giant tooth out of clay.
Use your imagination to determine what creature this one came out of, can even be human. Because of the nature of clay and the no thicker-than-thumb rule, we will be concaving the top (maybe the monster had a cavity?) which makes this tooth a lovely decorative dish or possibly shot glass.
We will start with a sphere of clay and pull and pinch the form from about a pound of clay. Then let your imagination run wild with whatever monster you want this tooth to come from.