The Bear is a special kind of Item that appears in Triple Town. It moves one space every time you place an item, blocking you from placing anything where it is. A bear turns into a Tombstone when it is trapped (when it has no more tiles it can move to), or when an Imperial bot is used on it. When there are three or more tombstones adjacent to each other, they form a Church.
Therefore, while bears can be quite frustrating, there are many uses for them. On the map A dangerous forest there are 50% more bears. In Peaceful valley there are no bears at all. It's common for a player to have many bears at once, thus making the game more challenging. An even more challenging version of the bear is the Ninja.