An I-Block (Also sometimes called a Line Piece) is a tetromino that is four blocks in a straight line. Therefore, it has the dimensions one block by four blocks. If rotated either way, the I-block will change orientations from vertical (1x4) to horizontal (4x1), and vice versa. The I-Block is a unique piece as it is the only tetromino that can cause a Tetris. However, it is quite rare to come in-game and thus must not be wasted.