Mount Etna is like no other volcano on Earth, new research finds. In fact, the volcano may have formed in a bizarre way, reminiscent of how some seamounts, called petit-spot volcanoes, grow on the ocean floor, researchers reported April 7 in the journal JGR Solid Earth . Although these seamounts are tiny —‬ just a few hundred feet tall — Mount Etna towers 11,165 feet (3,403 meters) above sea level. "This actually represents a new type of volcanism," Sarah Lambart , a petrologist at the University of Utah who was not involved in the new research, told Live Science. Before this study, researchers split volcanoes into three types, Sébastien Pilet , a lecturer in Earth sciences at the University of Lausanne in Switzerland, told Live Science. Mid-ocean ridge volcanoes form where the oceanic plate pulls apart and magma from below rises to form a new crust.…