Figure 7.18: This device, called a spectrophotometer can be used to measure the level of
radioactive decay of certain elements in rocks and fossils to determine their age. ( 9 )
Figure 7.19: Mole rats live under ground where they do not need eyes to find their way
around. This mole’s eyes are covered by skin. Body parts that do not serve any function are
vestigial structures. ( 22 )