84 THE OCEAN FLOOR 



In certain regions of the red clay area we might find 

 curious potato-hke or cauhflower-shaped brown to 

 black "mushrooms," the so-called manganese nodules, 

 slow growths of the abyssal field which may have re- 

 quired tens of thousands of years to attain the size of a 



Fig. 30. Radiolarians from Pacific depths 



golf ball. Very rarely the tooth of a giant shark or the 

 ear bone of a whale is also to be found there, covered 

 with a thin crust of the all-pervading manganese per- 

 oxide, the sugar coating of deep-sea confectionery. If 

 we were to bring with us a sensitive Geiger counter, we 

 would be surprised by the volley of radioactive particles 



