Question

How are casts formed by decaying organisms?

Answer 1

Cast fossils are formed when an organism dies and is buried between layers of mud and silt. The mud and silt form around what is left of the organism and slowly hardens and becomes sedimentary rock.  The buried organism decays and the hardened rock leaves an impression where the organism once was.  Lastly, mineral-enriched groundwater fills in the mold and hardens to form a cast fossil.

Answer 2

Answer:

its Impressions left by organisms are filled in with sediment that hardens into rock.

Explanation: