duck

        // count the next body piece number (wrapping to zero):
        bodyPieceNum++;
        bodyPieceNum %= bodyPieces.length;

        // place the next 'body piece' at the old head position
        bodyPieces[bodyPieceNum].position = transform.position;

        // move the head to the new position
        x += moveX;
        y += moveY;
        transform.position = Vector3 ( x * gridSize, 0, y * gridSize);