What Was That?

One of the workers felt something while he was checking the chimney with the stick. When he again touched it he told the team that it is kind of fluffy like a rug or carpet. The team then started to pull that thing down and that was their first mistake. These workers should have left the chimney alone because soon they would regret the decision. So what was it? A rug or something else? They would soon find the most amazing thing in the world.