How to Demonstrate a Mold Fossil

Present the mold fossil as is. Instruct your students that a mold fossil is superior to a fossilized bone, because a mold fossil represents the organism in its living form. A fossilized bone represents a dead organism. A mold fossil also captures plants like ferns, which were delicate and rotted away before they could petrify.

Create an alginate cast from the mold fossil. Mix dental alginate per the manufacturer's instructions, and spread it in a thick layer within the mold. Allow to harden per manufacturer's instructions. In minutes, you should have a perfect (albeit purple) representation of the living organism.

Create a wax model from the mold fossil. Simple beeswax melted in a pot will serve. Spread the wax in the mold, overflowing it, and allow to harden. Carefully loosen the mold fossil, for a perfect representation of the organism. Such a cast is not durable, but is useful for classroom demonstrations.

Create a metal cast from the mold fossil. First, create an alginate or wax cast cast as per Step 2 or 3. Mix Plaster of Paris per manufacturer's instructions, and press the cast into the plaster. Wait one hour for the plaster mold to harden, and remove the cast. Bake the plaster as per manufacturer's instructions (typically 150 to 200 degrees Fahrenheit, for 45 minutes). Melt pewter, lead or bronze in a melting pot, and pour into the plaster mold. You should have a durable cast of your mold fossil.