Dante tells the time...

Potato Clock!

How it works:

The copper, zinc and potatoes create a simple battery that makes the energy to operate the clock. The potatoes work as a device called a electro-chemical cell. It converts the chemical energy stored in the copper and zinc into electrical energy. Two potatoes are needed to power the clock. A cell works because of the chemical properties of the copper and zinc. The different properties cause tiny particles charged with electricity ( ions ) to move between the copper and zinc. This flow is called an electric current. The potato contains the particles that allow the current to flow, but stops the copper and zinc touching. Electric current also flows along the wires between the copper and zinc and the clock. This current makes the clock work.   
By Dante