Hello maggs, the structure is a so called "black smoker" which...

Hello maggs, the structure is a so called "black smoker" which form black "chimney" like forms.

"A black smoker or sea vent is a type of hydrothermal vent found on the seabed, typically in the abyssal and hadal zones. They appear as black, chimney-like structures that emit a cloud of black material. The black smokers typically emit particles with high levels of sulfur-bearing minerals, or sulfides. Black smokers are formed in fields hundreds of meters wide when superheated water from below Earth's crust comes through the ocean floor. This water is rich in dissolved minerals from the crust, most notably sulfides. When it comes in contact with cold ocean water, many minerals precipitate, forming a black, chimney-like structure around each vent. The deposited metal sulfides can become massive sulfide ore deposits in time."

https://en.wikipedia.org/wiki/Hydrothermal_vent