Final answer:
Living corals are found in warm shallow seas due to their mutualistic relationship with algae, providing each other with nutrients and sunlight. Coral fossils found in Alaska suggest the presence of coral reefs in the region in the past when the climate was warmer.
Step-by-step explanation:
Living corals are found within warm shallow seas because they have a mutualistic relationship with algae that live inside them. The algae provide the corals with the majority of their nutrition and energy through photosynthesis. In return, the corals provide the algae with a protected environment and access to sunlight. This relationship is important for the survival and growth of corals.
Although living corals are found in warm shallow seas, coral fossils have been found in Alaska. These fossils indicate that coral reefs used to exist in Alaska during a time when the climate was warmer and the region was likely located within the 30° north and south of the equator where coral reefs are typically found. Over time, geological processes such as tectonic movement and changes in sea level have brought these fossil corals to Alaska.