Terraforming, terra-reforming
In 2030s, the humans arrived on Mars. Humans were born on land, and they had lungs that could not extract the gas that humans need to continue their chemical life-fire. Not a problem. They brought with them cylinders of compressed life-gas, and life-gas producing creatures. They turned Mars green and covered its surface with life-gas.In 19th century, metallic horses were born on earth, and they had circular feet that could not trot over most kinds of land. No mountains, no grasslands, no marsh. Only hard flat surface of no more than 10 degrees in slope. Not a problem. Their human companion-species set out and terra-reformed the world for them. Now there are 10e10 of these metallic horses running wild on the hard flat surfaces over earth.
