What is the algae that is important in the formation of coral reefs?

The most important role of the algae when it comes to reef long term growth is directly reinforcing the limestone skeletons of corals with calcite, the hard mineral that forms the algae's skeleton. This allows coral reefs to maintain long-term structures that serve as the foundation of reef ecosystems.

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it has one origin of replication, but it proceeds in two directions - d)

plato users:

d.  

there was a variety of food available on island x, but there were only large seeds and nuts on island y.