Animating simple objects

I was wondering if you need to use a bone structure for animations for any object, or if you're able to animate and import without a bone structure into unity? I have some simple animations such as a treasure chest opening which I wouldn't normally use a bone structure system to animate. I've mostly ever done character animations so could use a few tips or a push in the right direction.

 

I think bone structure is better, but if your chest's structure is simple, you could just split the the chest into two GO ( lid and box ), and make the animation with UAW(Unity Animation Window)

 

Ya I was actually just thinking about this earlier, since it is very simple. I have never really messed with the built in animation tools but from what I've seen before it looks basic. Will give it a try.