A man hiking through Arizona captured video of a bizarre "once in a lifetime" scene -- a rattlesnake hitching a ride on the back of a desert tortoise.

Mario El Pachuco said he was hiking in Pima County when he stopped to take some photos of a desert tortoise.

"As I got closer, a head came out from behind his shell and that's when I noticed the snake," he wrote. "I started taking pictures and the snake just started slithering on top of the tortoise as you see on this video."

The video shows the tortoise take a casual stroll while the snake rides on its back.

"I don't know the reason why this tortoise and the rattlesnake were together but I'm glad they were," El Pachuco wrote. "It is not uncommon for rattlesnakes and tortoises to share the same burrows but I had never seen them hanging out in the open like this."