The calcium carbonate in my cells gives my body some support and makes me a pretty tough plant. It also makes me less tasty to some animals. However some animals, like fish and snails, still think I am delicious! I provide a home and a good hiding place for many small invertebrates and fish, so it's important that I am all around the reef.
People don't think plants do much, but I am an important reef builder! I am a special plant because I have calcium carbonate in my cells (that's what calcareous means). Calcium carbonate is also known as limestone. It's kind of like concrete and is made by lots of other animals too. It is what makes the reef hard and strong, like a rock. When I die, the calcium carbonate in my cells will become building material for the reef.
Plants are totally the coolest animals on the reef because we don't have to eat. I make my own food using sunlight in a process called photosynthesis. During photosynthesis I take carbon dioxide and energy from the sun and convert that into sugar and oxygen. Plants on land do this as well. (This, of course, makes land plants just as cool as reef plants like me!) Because I make my own food, I am a producer.
There are no threats to me yet, but the ocean is starting to become more acidic. Imagine if all your drinking water had sour lemons squeezed into it! That's kind of what its like when the ocean has a high acid levels.. If that happens, then it will be more difficult for me to make my calcium carbonate and to grow! If I can't grow well, then the reef can't either and all the small animals that live in and near me are threatened, too.