The Square on Strings is the most commonly distributed member of the String Obstacle class. It is found in Checkpoint 3 multiple times and in Checkpoint Infinite (Endless Zone). It is the 2nd member of its class. There are 2 ways to clear them out of your wat\y. Because you do not have Explosive Balls on Checkpoint 3, you need to disconnect it from at least 2 of its strings. Way number 2 is to get close to them, then fire in front of your perspective so you don't get hit and by performing both of these ways, you won't lose 10 balls + your current ball streak. Their stronger counterpart, the Painting, is stronger because of metal in the center. They are defeated the same way, too. They are only seen in the black color.