What does a World War II nickel look like?

It has the same design as other Jefferson nickels minted from 1938 to 2003, except that the mint mark was made larger and placed above the dome of Monticello on the coin's reverse. In addition, a "P" mint mark was used for Philadelphia coins. This was the first time a P had appeared on any US coin; its use was resumed until 1979/1980.

War nickels were made of an alloy of 56% copper, 35% silver, and 9% manganese. When new the coins looked almost like their cupronickel counterparts, but as they tarnished the manganese tended to turn gray. They were also softer than cupronickel coins so they wore more quickly.