It's a whole underwater ecosystem with bacteria, tubeworms and other creatures crowded around the hot water vents. Like the volcanoes above water, the underwater vents spew lava. Over time the lava cooled and formed underwater caves. Dr. Tunnicliffe describes what she saw. The eruption caused an earthquake that measured 4.8 on the Richter scale and it heated the water so much that the temperature change could be measured on the surface far above.
Bacteria can breakdown hydrogen sulfide and use it as energy.
They coated the area soon after the volcano erupted. Dr. Tunnicliffe says that the bacteria are usually hard to see, but near these vents they grow in thick white mats. Scientists aren't sure where the bacteria come from. One theory is they actually live under the surface of the rock where they grow, and breed until an eruption pushes them out. What scientists are sure of is that the bacteria are a food source for the other underwater creatures.