Creeping Cacti

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

Description
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.