Experiments with Eggs: Metal Glass Egg 

Explanation: Metal Egg demonstrates various concepts of Light, Chemistry, and properties of matter. The experiment actually does not turn the egg into real metal, but it appears to be so under water. It’s an optical illusion! The charred egg actually gets covered with a layer of soot, which is carbon from the wick of the candle. The carbon in the soot, being hydrophobic repels the water. This holds a fine film of air around the egg. When light falls on the underwater egg, it gets refracted thus giving it a metallic appearance. 

Source: https://www.zlifeeducation.com/blog/metal-egg/