Have you ever played with dry ice (with leather gloves on of course!)? Perhaps you’ve made Halloween punch? Set a spooky scene? The fun comes from the fact that dry ice goes directly from solid to vapor, unlike water ice, which melts into liquid when it gets warm.
On Mars, the seasonal polar caps are composed of dry ice (carbon dioxide). In the springtime, as the sun shines on the ice, it turns from solid to gas and causes erosion of the surface. “Spiders,” “caterpillars,” or “starbursts,” can be colloquial words for what is actually called “araneiform” terrain.
This particular example shows eroded channels filled with bright ice, in contrast to the muted red of the underlying ground. In the summer, the ice will disappear into the atmosphere, which leaves just the channels carved in the surface. This is truly Martian terrain: This type of erosion does not take place anywhere naturally on earth because our climate is too warm.