Molar tooth, coloured scanning electron micrograph (SEM). The molars are broad ridged teeth found at the back of the jaws of mammals. The ridges are used to chew and grind tough food. The highest points of the ridges are known as cusps. This is the crown, the visible part of the tooth. It is covered in enamel, the hardest substance in the human body. Magnification: x11 when printed at 10 centimetres wide.