In the same way logos are recognized before they are read, the shape of a logo is one of the key identifiers for a brand. Thanks to graphic designer @DavidAirey, I stumbled across this great experiment at Brand Spirit where they painted common items completely white and removed all their visual branding reducing the object to its purest form - it's shape.
Like the recognizable shape of Apple's iconic logo to the curves of a Coca-Cola bottle, shape is one powerful signal to the identity of a brand. Take a look, and without color and text, you may see something you never even noticed before. (btw, the Atari 2600 joystick is a work of art!)