No, you don't have to open it. It has a strong sweet lemony aroma. It is used in Asia to make a room fragrant. Wiki says they are used to make candy as well as an addition to Vodka for the avoidance of Scurvy.
And, if you think they look creepy, can you imagine a tree with a bunch of these hanging down? I've never seen one, but I'd hate to run into one on a dark night.