Jumping Cholla

Never heard of these before, a cactus that seems to jump at you to stick its thorns into you. Once it makes contact it detaches that piece.

Sounds far fetched, but Trish swears she didn't touch it, but it got her good. Stuck onto the back of her hand it was very difficult to remove, and painful. Several days later her fingers were still feeling it.

I didn't take a picture of Trish's attack, or the bloody result, but the below picture found on the web kind of illustrates it.