While playing on different levels you may find you have created a special piece.

Match 4 pieces in a square shape to create a spiral piece that will fly across the board and remove/damage a random tile
Match 4 horizontally or vertically to create a piece that will clear an entire row or column
Match 5 to create an exploding tile that will destroy up to 9 tiles directly next to it
You can also combine special pieces together to get a bonus!

There are others to find as well. Will you be able to discover them all?