Fossil:any remains,impression,or trace or a living thing or a former geologic age,as a skeleton,footprint
Mold:a hollow form or matrix for giving a particular shape to something in a molten or plastic state
Cast:to receive form in a mold
Trace fossil:a fossilized track,trail,burrow,boring,or other structure in sedimentary rock that records the presence or behavior. If the organism that made it