Definition: The term "graptolithina" refers to a type of organism that is characterized by its presence in the sedimentary layers of marine organisms. These organisms are known as graptolites, and they consist of tiny, flattened structures called graptoliths. Graptoliths are formed when certain types of bacteria or algae attach themselves to the surface of rocks, gravel, or other sedimentary materials. Over time, these graptoliths can become cemented together into larger structures,
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