Mystery Bug

While I was sitting on the rooftop this morning, reading, reflecting, praying, I noticed a wiggle on a flowerpot. At first I thought it was the wind blowing a leaf, but it was more of a regular wiggle than that. After staring at it from a distance for a while, my curiosity got the better of me and I had to get a closer look.

What I found was half a caterpillar sticking out of a leaf-like cone. Somewhat like a hermit crab poking out of his shell. (Can you see his little head on the right side of the picture? Sorry, I know it's small.)

I've never seen anything like this. It was the most peculiar thing. The leaf cone was completely attached to him but looked like real leafs. Even when he was crawling on the underside of a branch, it stayed hanging on his back end.

Have you ever encountered something like this? Do you know what it is or have an explanation?