They are part of a system of underwater hot springs, called hydrothermal vents, which are found on volcanic mid-ocean ridges where the Earth's tectonic plates meet.
(They; are; part of a system of underwater hot springs) (underwater hot springs, called hydrothermal vents; are found; L:on volcanic mid-ocean ridges) (the Earth's tectonic plates; meet; L:volcanic mid-ocean ridges)
They underwater hot springs, called hydrothermal vents the Earth's tectonic plates
are are found meet
part of a system of underwater hot springs
L:on volcanic mid-ocean ridges
L:volcanic mid-ocean ridges