How fast does tropical black coral grow?

Question

how many feet per year perhaps?

Answer 1

It grows an acre an hour and is free for the taking.

Answer 2

Black corals grows up to 6.5 cm / 2.5 inches each year.

Black corals are found all around the world even if the are most common in tropical and subtropical seas. Different species of black coral can be found from shallow depths of 1m/3ft to depths up to 6000 m / 20 000 ft where no light can reach them. Black corals are often found in dark areas where they are exposed to relatively strong currents. The corals are dependent on these currents to bring them plankton to eat. It seems that the primary factor that controls the re growth within the populations of black corals are the availability of suitable habitats. Black corals larvae seem to be sensitive to light and that the corals therefore prefer relatively dark habitats. This theory is supported by the fact that black corals are found in much larger numbers below a depth of 35m/ 120ft where less light is able to reach them. Black corals also lack symbiotic algae that many other corals keep which makes them more adapted to live in deeper darker waters