The Martians travelled to Earth and found that the planet’s oceans were filled with sharks of all different kinds. Big ones, small ones, ones with polka dots, ones with stripes, and their bones were all filled to the brim with calcium marphondulate. Once the Martians found Earth’s conditions preferable to that of Mars, they began their big move. They set up civilizations along the beach and continued to eat without ever worrying about running out of sharks.
However, they did have to worry about Earthlings getting in their way! Earth’s leader at the time, the Hominoidea crown princess affectionately nicknamed Sweetthing by her people, ruled with an iron fist and was quite used to fending off alien invaders. She also had quite the soft spot for her Shark population, as they kept her oceans clean by consuming any carcasses, and was appalled upon seeing them massacred.