My guess is that most of the bricks you’ve seen in your lifetime have been very uniform in shape. Each brick is rectangular. This is by design in almost all cases. The length of a brick plus one mortar joint in the USA is supposed to equal 8 inches. The depth of a standard brick plus a mortar joint is intended to measure 4 inches. The height of three bricks plus three mortar joints equals 8 inches. This is why many common bricks are referred to as modular.
That said, funny things can happen at a brick factory that might have an older kiln or one that’s not designed to heat the contents evenly. A brick might develop a nasty blister and swell up once it’s fired in the kiln. Some can twist and deform. Some develop severe discoloration. This deformation and discoloration are attributed to the excessive heat some bricks experience in the firing process. Brick manufacturers call these clinker bricks, as they make a distinctive sound when they tumble against one another.
