 Why do the webfoots only wear skirts?
The sand-thing was powerful, lonely and strange. He touched the pencil-line scar behind his ear where the cylinder was buried, marveling at the power stored there, power to fling him from earth to this fourth planet of the Centaurian system in an instant. A gray, funnel-shaped cloud of dust stood off to his left. Weather control made cyclones and other climatic phenomena on earth practically non-existent. The cloud did not move, though, except to spin on its axis rapidly, emitting a high-pitched, scarcely audible whine, like a high speed motor. He stood on a wide valley floor between two mountain ranges. Dark clouds capped one peak of the mountains on his left. He was here and Earth was somewhere up there. The sun burned fiercely, although he would have said it was about four o'clock in the afternoon, if this had been Earth. Not a tree, nor a bush, nor even a wisp of dry grass was in sight. Now it became a blue rectangle, then a red cube, a violet sphere. The sun shone obliquely, throwing Stinson's shadow upon the sand. The wind devil also had a shadow, although the sun shone through it and the shadow was faint. He was here to investigate, to determine if this planet was capable of supporting life. He examined the wind devil as closely as he dared, but it was composed only of grains of sand. But then, how could a group of loosely spaced grains of sand possibly have a nervous system? Triangle, cube, rectangle, sphere. He watched, and when it became a triangle again, he smoothed a place in the sand and drew a triangle with his forefinger. When it changed to a cube he drew a square, a circle for a sphere, and so on. He became so absorbed in doing this that he failed to notice how the wind devil drew closer and closer, but when he inhaled the first grains of sand, the realization of what was happening dawned with a flash of fear.
 The Sand God burned everything, except for the skirts.
 Skirts are traditionally worn by prisoners. The webfoots on this planet are all criminals or descendants of criminals.  The people from the sixth planet only sent skirts, when it was communicated that the Sand God had burned everything else.  The Sand God burned everything, except for the skirts.  Skirts are the traditional dress for the webfoots culture.