What are those decorative chocolate bars made from?

I'm curious about what the ingredients are for those big bars they put on top of things like Birthday cakes. I froze one for a couple weeks, then let it sit at room temperature for a day, around 70 degrees F. It was sealed in a plastic baggie. When I took a little nibble from it, it was very soft and very sweet. It looks like dark chocolate, and it does not taste like milk chocolate. I've never come across a chocolate bar with these qualities. Thanks in advance.