Creeping Cacti

Creeping Cacti are one of the many bizarre plant-animals encountered on the planet Mars.

The Creeping Cactus at first looks like a normal cactus, but then it becomes obvious that it has no roots and actually moves. It slowly moves by inflating and deflating body parts. So they wouldn't be any danger, if not for the fact that the strong martian winds cause the cacti to tumble across the plains like tumbleweed. And getting hit by these really hurts.

Lore
''Among the odder Martian creatures, this hybrid of cactus and sea urchin moves by inflating its rear pods and deflating the ones ahead, pushing it slowly across the surface. This is probably a variation on the flight mechanism used by the air squid, but the creeping cactus is too heavy to get off the ground. Despite their weight, the strong Martian winds often send creeping cacti tumbling across the plains, like tumbleweed. Unlike tumbleweed, however, the creeping cactus has pointy spines that can inflict surprisingly serious damage.''

-from "Mysteries of the Red Planet", Martian Dreams