Answer:
the answer is D, they both develop calcium carbonate structures
Explanation:
The Ordovician is best known for its diverse marine invertebrates, including graptolites, trilobites, brachiopods, and the conodonts (early vertebrates). A typical marine community consisted of these animals, plus red and green algae, primitive fish, cephalopods, corals, crinoids, and gastropods.
Answer:
physical change
Explanation:
They are formed from pieces of other rocks or organic material