Satellites spot clusters of 'spiders' sprawled across Mars' Inca City (photo)

Seasonal, spider-like features have been spotted sprouting through cracks in Mars' surface. The European Space Agency's Mars Express orbiter captured new images of small, dark features that resemble spiders scuttling across the Martian region known as Inca City near the Red Planet's south pole. This phenomenon appears when spring sunlight warms layers of carbon dioxide deposited during the dark Martian winter. In turn, carbon dioxide ice in the bottom layer turns into gas, which builds up and eventually breaks through …