Corals are organisms that have no backbone. These are found under water – mostly in seas/oceans.
Coral reef is an underwater ecosystem of which Corals,of course, are an integral part.

Coral reefs provide shelter for several marine organisms. These are also the source of nitrogen and other essential nutrients for marine food chains. In a nutshell, these maintain the ecological balance of the oceans.
However, the ever increasing shipping activities pose a threat to these reefs. When ships ply over the areas where corals are present, these reefs get destroyed.
Of late, there have been enhancements in the operations for shipping to ensure that the coral reefs are not impacted.
Ever seen a floating buoy in the sea ?
These are like a speck floating in the sea. Earlier these were meant to just for directions while traveling in the sea. With the increased awareness about marine ecosystem, engineers have been able to design buoys that can be used to anchor ships at optimal distance from the coral reefs.

These are called Mooring buoys.
Its quite impressive when technology is used to find solutions.
How it complements itself is just amazing !