The National Environment Agency (NEA) will be relocating more than 600 coral colonies from Pulau Semakau's Phase II Lagoon to Sisters' Island to make room for a new landfill cell that is meant to help meet the waste disposal needs of Singapore up to 2035 or beyond.

This relocation is expected to take four months, with the first month dedicated to coral harvesting and the following three months for coral attachment at two recipient sites at Sisters' Islands.

All the 600 colonies fall under 27 genera, or families, of corals. They include several rare genera like Polyphyllia and Heliofungia.

We take a look at the five rarest coral families out of these 27.

Polyphyllia

The rarest of the lot, the Polyphyllia genus comprises approximately 11 nominal species but only one (Polyphyllia talpina) is found on Singapore's reefs.
The Polyphyllia genus is, for the most part, a free-living creature that is quite mobile. The body or bone structure can be flat or arched. They are long and thin and can be shaped like a tongue, a boomerang, or a T, X, or Y shape. A member of this genus is usually brown or gray, sometimes with cream or green. The base tissue ranges from fluorescent green to teal. Their tentacles are usually brown with white tips, and sometimes have forked ends.

Heliofungia

The Plate Coral, Heliofungia actiniformis, is the only member of its genus. It is easily distinguished by its large, long tentacles topped with knobby tips. They are usually brown or olive with white tips, but sometimes are bright green, dark purple, or yellow. Pink tips and solid pink tentacles are also common. With their long flowing tentacles, which are extended throughout the day, they are often mistaken for anemones.
On the reef, these corals generally inhabit shallow areas in calm lagoons on sandy or muddy bottoms.

Pavona

The Pavona genus contains some of the most autotrophic species known to science. Autotrophic is the ability to take simple inorganic substances such as carbon dioxide and turn them into nutritional organic substances that can then be used for food.
Pavona species make up for environments with less light by absorbing more nutrients, yet under bright light, they do well without direct feedings. Hence, they tend to be tolerant of most adequate aquarium reef habitats, thriving under less intense lighting, and are fairly disease resistant.
This coral can be bright orange, green, pale grayish brown or dark grayish brown.

Psammocora

Psammocora corals grow in a combination of forms, including flattened branches, column formations, and irregular nodules. When their polyps are retracted, the corallites on the surface create flower or star-like patterning.
They come in pale to dark grayish brown and green shades.
Some general names for the Psammocora genus are Pillar Coral, Cat's Paw Coral, Encrusting Sandpaper Coral, and Starry Petaloid Coral.

Goniopora

The Goniopora corals have a very distinct appearance. These corals have several common names that reflect their appearance. They look much like a ball or cluster of potted flowers. Hence they are often known by names like Daisy Coral, Flowerpot Coral, Sunflower Coral, and Ball Coral.
All the different Goniopora species have 24 polyps, but they are usually of different shapes and colours. A polyp is an extended piece of tissue growing from the surface of the coral. The species in the Goniopora genus extend their polyps during the day, but retract them partially at night.
Their colours are usually green or brown, but can include shades such as brown, pink, red, cream, yellow or gray.

Information culled from National Environment Agency, Professor Chou Loke Ming and http://animal-world.com/.