What Is a Coral Reef?

Coral reef is built by corals and by algi, which are captive in their cells. Coral can grow between a centimeter and and rafty ten centimeters a year depending on the species. A reef itself will grow probably five to eight millimeters a year if it's in healthy condition. The deepest parts deposited millions of years ago. So over that time, they'e grown up. Now they're marine animals, so they cannot grow above the low water mark. They re sow round the world, reach the low water point at the highest an and there's a constant battle between erosion and growth,. And you have the growth of the corals, which are secreting.