The United States Mint explains there are only about 40 copper–alloy cents that exist today ... piggy banks and start looking for a rare 1943 penny, here are some key features that will help ...

Certain pennies are more valuable than others. A copper penny from 1943 is valuable. At this time, steel was used to make pennies instead of copper because copper was needed for the war effort.

Like the 1943 copper penny, it was struck using the wrong planchet. By 1944, the U.S. Mint returned to only using copper alloys to mint pennies, but a few were accidentally struck with the steel ...