how are a mold and a cast related

Question

PsyDAG · Accepted Answer

From Google:
When organisms are buried in sediment they may decay or dissolve away leaving a cavity or what we call mold, if the pace is filled with sediment, then an external cast is made. A mold fossil becomes a cast fossil when it is filled with sand or mud and hardens.

Art Nerd · Answer

Thanks PsyDAG I can use this as a mini reference :)