Mold fossil formed when remains trapped tree sap cast fossil impressions from very

Amber fossil is formed when remains are trapped tree sap 

Petrified fossil are preserved remains that are transformed into rock.

Imprint fossils are impressions from very thin objects trapped in mud and transformed into rock.

Trace fossils are preserved records of life like a footprint or a trail imprint fossils a raised fossil that has filled in the impression from.

Mold fossils are formed when remains of living things leave an impression on a rock.

Cast fossils are a raised fossils that have filled in the impression from a mold.

Explanation:

A good index fossil is one with four characteristics: it is distinctive, widespread, abundant, and limited in geologic time. Because most fossil-bearing rocks formed in the ocean, the major index fossils are marine organisms. That being said, certain land organisms are useful in young rocks and specific regions.