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THE NATIONAL GEOGRAPHIC MAGAZINE
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| FRAGMENTS OF A COLONY OF MARINE ANIMALS ON A SLAB OF BLACK ROCK, WITH MANY TRILOBITES (DARK) AND SHELLS OF THE SIDNEY CRAB (LIGHT), WHOSE CLAWS ARE SHOWN ON PAGE 517 These creatures and other animals, like the delicate jelly-fish, have been preserved many millions of years while sediment several miles deep was deposited over them (see page 511). Photo by Thomas W. Smillie. |
