What is the diversity of other corals in Hong Kong?

Gorgorian found at Port Island Black Coral found at Tung Ping Chau

In addition to stony corals, there are soft corals, gorgonians, black corals, sea pens and so on in Hong Kong waters. However, we don't know much about them, except the following two:

There are 26 species of gorgonians from 15 genera in Hong Kong waters. Gorgonians prevail in the eastern waters of less variable salinity. They require a firm substratum for anchorage and reach maximum abundance at about 20-25m deep.

Eight species of black corals from 2 genera have been recorded in Hong Kong waters. Most of them found in north-eastern waters at depth of 10-20m.