How much is a penny worth that has star fish on the back?

There's no such thing as a US penny with starfish on the back.

Here's why:

* Penny Design: US pennies (one-cent coins) typically feature Abraham Lincoln on the front and the Lincoln Memorial on the back.

* Starfish Symbolism: Starfish are not associated with any US coin designs or significant historical figures.

It's possible you're thinking of a different coin or a coin from a different country. If you can provide more details about the coin (like the year, metal, or any other markings), I might be able to help you identify it!