When sedimentary rock go to the bottom of a seafloor it sticks together over time and turns into metamorphic rock. Then metamorphic rock melts and when it cools down it turns into igneous rock. This process happen over and over and its called rock cycle.
Answer: They existed for a short span of time.
Explanation:
Index fossils are also referred to as the indicator fossils and they are simply used to define the faunal stages.
Some of the characteristics possessed by the index fossils include:
• geographic distribution that's wide
• short vertical range
• rapid evolutionary trends.
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