#SpidersofMars The Spiders of Mars (a la Ziggy Stardust) these gargantuan beasts roamed the surface of the red planet for millions of years before the age of man, living for millenia and reshaping the surface with their feeding and migratory habits. Their massive forelimbs were fused together and evolved into a highly specialized shovel-like protrusion, which was used to plough through the martian soil scooping up the microbial life abundant in those times (much like the plankton in Earth's seas). The disturbed soil was swept through a gaping maw, passing fine tendrils that acted as filters. Ingesting the microbes created methane gas, which swelled the Spiders' abdominal sack and helped bouy their massive weight. The barren soil was expelled behind. Because these creatures followed the exact same feeding path their entire lives, they eventually wore channels, then canyons into the planet's surface, dying out only when the soil refused to yield any more nutrients.