What about pennies that look nickel plated?

Pennies are often plated for use in jewelry or as novelty items. That makes them altered coins worth only 1 cent.

However, cents dated 1983 or later, and some 1982s, are made of copper-plated zinc. Sometimes a high school student will dip a penny in acid and dissolve the copper. That again makes it a damaged coin.

There's still a third possibility: every once in a while a cent doesn't get copper-plated at the mint. That's a genuine error coin and can be worth up to $100. However such a coin has to be inspected carefully to make sure it isn't really one of the other 2 possibilities.

Pennies were also made of steel during WWII