A coral is made up of thousands of invertebrate animals that form one structure. They feed either by taking food from algae that live in them or by capturing small animals that drift around them.
Many corals that grow together form reefs which, in turn, support a staggering amount of life, both animal and human.
Singapore has lost about 60 per cent of its reefs due to land reclamation over the years. Despite the loss, its waters are home to about one-third of the world's hard coral species.
This is because Singapore sits near the Coral Triangle, an area spanning the seas of Malaysia, Indonesia, the Philippines, Papua New Guinea, Timor-Leste and the Solomon Islands. The area is considered to be the largest and richest treasure trove of marine life on the planet.
THREATS TO OUR REEFS
Economic development has destroyed most of Singapore's existing reefs and, coupled with intensive land reclamation, this has led to murky waters off the country's shores. In the 1960s, Singapore's seas used to be clear enough that marine life up to 10m underwater was visible from a boat.
The sediments that are built up over the decades interfere with the corals' ability to filter water, as well as reduce the sunlight that reaches the algae that live inside these corals and provide them with food.
Another big threat is coral bleaching. Linked to climate change, this occurs when the sea becomes too warm for corals, causing them to expel the algae living inside them. As a result, the corals, deprived of their food source, turn pale white. If bleached for too long, the corals will die.
The reefs around Singapore also face dangers from the many ships that ply the waters, which can crash into them and kill them.
Divers can join Our Singapore Reefs and the Hantu Bloggers, groups dedicated to promoting awareness of the country's reefs.
The National Parks Board also runs programmes for those passionate about reefs and who do not necessarily dive. For example, volunteers can sign up as guides, citizen scientists and divers at Sisters' Islands Marine Park.
They can also join the Coral Reef Monitoring Programme, which checks the health of underwater habitats in the Southern Islands.
There are also opportunities for those who want to help related ecosystems. TeamSeagrass, for example, monitors Singapore's seagrass meadows during low tide throughout the year.