Final answer:
Coral reefs are large masses and ridges of limestone rocks containing animal shells, formed by marine invertebrates like corals, which secrete calcium carbonate skeletons. They provide important habitats for ocean life and are prominent features in warm, shallow marine environments. Option c. is correct.
Step-by-step explanation:
Large masses and ridges of limestone rocks that contain the shells of animals are known as coral reefs. A coral reef is an ocean ridge formed by marine invertebrates living in warm shallow waters within the photic zone. Notably, corals are colonial cnidarians that secrete calcium carbonate to form their skeletons. Over time, these skeletons build upon one another, creating vast structures called coral reefs. They serve as important habitats for a diverse range of ocean life and are resistant to waves, standing above the surrounding seafloor.
Coral reefs can be found in various global locations such as the Great Barrier Reef in Australia and are built from living organisms including corals, which are sessile polyps. These organisms can feed on ocean creatures passing by using their tentacles, and contribute significantly to the reef structure with their limestone skeletons.
The geological aspects of coral reefs indicate that they are made up of the remains of clams, corals, and other creatures which use calcium carbonate for structural purposes, such as shells. This calcium carbonate over time accumulates to form the coral reefs we see today.