Fossil Types and Fossil Formation

Mold Fossils

A cast fossil is formed when a mold fossil is filled in with mud or sediment that hardens over time, leaving a replica of the original organism.

Cast Fossil

Mold fossils form when all or part of an organism was pressed into soft mud, leaving an impression or indentation that hardened over time.

Trace fossils do not include the remains of an organism, but are clues that an animal leaves behind. Footprints are an example.

​

Trace fossils

A body fossils are the remains of an entire organism, including the hard and soft parts. This happens when an organism is frozen or dried out.

​Body Fossils (true form fossil)

Multiple Choice

Which example is NOT a trace fossil?

Multiple Choice

Which type of fossil forms when the entire organism is preserved, including the hard and soft parts?

• Trace fossil

• Mold fossil

• Body fossil

• Cast fossil

Multiple Choice

Is this a mold or cast fossil?

• Mold

• Cast