Look closely at a standard USB plug. The strange geometric symbol carved into the metal is actually modeled after what?

A trident, adapted for a cable

The USB symbol is modeled on a trident—the three-pronged spear traditionally associated with Neptune, the Roman god of the sea. Its branching shape makes the emblem easy to recognize on a plug or port, even when the connector itself is small.

Why the prongs end in shapes

Instead of three identical points, the emblem’s branches end in a circle, a square, and a triangle. These geometric tips give the logo its distinctive look; they are not a diagram of the plug’s internal wiring. The symbol’s trident form suits USB’s role as a general-purpose connection: one familiar mark appears on ports and cables used for many kinds of devices.