Class: Anthozoa (anemones and corals)
Subclass: Octocorallia (Octocorals)
Order: Alcyonacea (the soft corals)
Corals of the family Paragorgiidae are commonly referred to as bubblegum coral, due to masses of bulbous branch tips (these are the actual polyps) and comparatively bright colors ranging from plain white to pink, purple, red, or orange. They have a strong central trunk attached to the seafloor, and fan out quickly into a number of feathery or serpentine arms. This is a situation where a picture is worth a thousand words, so take a look at these.
These corals prefer deep water -- depths between 200 and 1,300 meters -- but can also be found along rocky coasts at shallower depths; for example, the Norwegian fjords are known for having corals at ~40 meters, and some of the most striking of these are Paragorgia arborea. They prefer temperatures between 2 and 8 °C (36 and 46 °F), although this may vary across species. They adhere rather than 'root', and so require a hard bottom to attach to, and are found most often on continental shelves and seamounts. They have been observed to grow up to 6 meters in height, and have central stalks as big as tree trunks. They grow either into large fans or dense, bushes, and look quite fluffy when all the polyps have their feathery tentacles out for feeding. One individual was radiocarbon dated at 300-500 years old, although this was a particularly large specimen; there is comparatively little data on the average lifespan of these corals.
The most common species worldwide is Paragorgia arborea, which is found in the Pacific, Atlantic, Indian, Arctic, and Southern oceans, although it avoids the tropics. Determining that all these populations belonged to a single species was an early triumph of genetic sequencing in marine biology. Because of this, many people will treat Paragorgia arborea and 'bubblegum coral' as synonyms. However, there are currently 24 recognized species in two genera, and more are likely to be discovered. Admittedly, the differences between species are rarely apparent to non-biologists.
Due to their wide range and firm rooting (both to the seafloor and to vertical rock faces), Paragorgiidae is also of interest as a habitat for a number of associates. Crinoids, basket stars, and squat lobsters live in them, waiting for the current to bring them something to eat, copepods and polychaetes are common parasites, and anemones and sponges attach themselves to dead branches. Bubblegum corals and their associates are often damaged by bottom trawling, and some jurisdictions are starting to put more protections in place to preserve deep water corals and their habitats.