Blue coral or Heliopora coerulea is a coral

Coral

Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...

. It is the only species in the family Helioporidae and the only Octocoral known to produce a massive skeleton. This skeleton is formed of aragonite

Aragonite

Aragonite is a carbonate mineral, one of the two common, naturally occurring, crystal forms of calcium carbonate, CaCO3...

, similar to that of scleractinia

Scleractinia

Scleractinia, also called stony corals, are exclusively marine animals; they are very similar to sea anemones but generate a hard skeleton. They first appeared in the Middle Triassic and replaced tabulate and rugose corals that went extinct at the end of the Permian...

. Individual polyps live in tubes within the skeleton and are connected by a thin layer of tissue over the outside of the skeleton.
It is a common member of shallow coral reef

Coral reef

Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...

s and is found extensively throughout the Indo-Pacific

Indo-Pacific

The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...

 including Ryukyu Islands

Ryukyu Islands

The , also known as the , is a chain of islands in the western Pacific, on the eastern limit of the East China Sea and to the southwest of the island of Kyushu in Japan. From about 1829 until the mid 20th century, they were alternately called Luchu, Loochoo, or Lewchew, akin to the Mandarin...

 in southwest Japan, Coral Sea

Coral Sea

The Coral Sea is a marginal sea off the northeast coast of Australia. It is bounded in the west by the east coast of Queensland, thereby including the Great Barrier Reef, in the east by Vanuatu and by New Caledonia, and in the north approximately by the southern extremity of the Solomon Islands...

 in northeast Australia and American Samoa

American Samoa

American Samoa is an unincorporated territory of the United States located in the South Pacific Ocean, southeast of the sovereign state of Samoa...

. The largest blue coral colony in the world is thought to be off of Ishigaki Island of the Yaeyama Islands

Yaeyama Islands

The Yaeyama Islands are a group of islands in Okinawa Prefecture, Japan.The isles are the remotest part of Japan from the main islands and contains Japan's most southern and most western inhabited islands.The islands form the southern part of the volcanic Nansei Islands...

, in southwest Japan.

Due to its unusual blue colour and being fairly tolerant of conditions it can be used in tropical aquariums.

A syrup extracted from the coral is commonly used in "Bubble Tea" drinks found in and around south east Asia.

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