What penny sold for $2.5 million?

Excuse me, could you elaborate on the fascinating story behind the penny that was sold for an astonishing amount of $2.5 million? I'm genuinely intrigued to know what made this particular penny so valuable and sought-after in the market. Could it be a rare coin with a unique historical significance, or perhaps a collectible item with exceptional condition? I'm eager to understand the factors that contributed to its exceptional value and what sets it apart from other pennies.