Answer:
Useful
Step-by-step explanation:
Index fossils are believed to be useful in correlating rock strata from widespread locations.▸ The collection of such fossils from different rock formations and layers enables the geologists to identify the layer of rock they were found in.
▸ They are also useful in dating and the study of geological formations which help scientists to get a clear understanding of the environment and the life forms that dwelt on the planet even hundreds of millions of years ago.
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