Tumbleweed

Tumbleweeds are world objects in Fallout: New Vegas.

Gameplay
Tumbleweeds roll around the Mojave Wasteland, they appear as balls of golden-brown weeds, which occasionally can get stuck on objects in their path. They are very light, and can be picked up and moved around. Jumping on them emits the same noise as when stepping on metallic surfaces. They can be shot, doing so results in a metallic noise, and may propel the tumbleweed into the air.

Radioactive tumbleweed

 * A radioactive version of the tumbleweed exists within the resources of Fallout: New Vegas, but remains unused. Identified as Radioactive Tumbleweed, it emits radiation similar to a glowing one, is classified as a creature, consequently moves under its own power, and can be killed.

Wind Brahmin

 * A creature version of the tumbleweed also exists but remains unused. It is identified as "Wind brahmin."

Bugs

 * Occasionally tumbleweeds may be found frozen in place almost as if they were scenery or partly sunken into the ground and stuck, jumping on top of them still yields a metallic sound, but they will not move. Sunken tumbleweeds will remain that way indefinitely, with no known way to free them.
 * If picked up and shot with a high powered weapon, it will fly high enough that it gets stuck in the sky, appearing as a tiny grey smudge easily mistaken for dirt on the screen.