The Cocoon Ate My Lawnmower

I went outside with the dogs a few minutes ago, and it is so nice outside! So I thought maybe I would mow part of the lawn. I went to the garage door, and looked it over carefully, like I always do, because I have a lot of spiders where I live, and I definitely don't want to take the chance of touching one or having one fall on me or anything. Shudder. And I did find some spiders, but I also found this:

(Shown next to a Daddy Long Legs, so you can get an idea of the size of it - it's very small.)

It's a cocoon. Or chrysalis - I'm not sure. Whatever it is, I don't want to take the chance of hurting it, so I didn't open the garage door, and my lawn didn't get mowed. I wonder how long this thing will be holding my garage door captive?

If anyone who reads this has any idea what type of creature this is going to end up being, drop me an e-mail or a comment, would you? I'd really like to know. Thanks!

Edited to add: I did some research online, and it looks like it's a Monarch butterfly cocoon! So exciting. It takes them about a week and a half to come out of the cocoon. I have no idea how long it's been hanging there, but I'm going to keep an eye on it. Apparently they turn transparent a day before they emerge, so when it gets to that point, I'll take another picture. But, yay! My garage door is hosting the birth of a Monarch butterfly! So cool.