Piece of resistance

The Piece of Resistance is first shown when Emmet falls in the hole in the construction site and when he touches it, he ends up in Bad Cop's office.

It is first introduced when Vitruvius talks about it in the Prophecy which is made up.

Appearance
The Piece of Resistance appears to be a red cap to the Kragle, or Krazy Glue and it attaches on to whoever touches it, that was Emmet.