What is a mold of a shell?

A mold of a shell is a geological formation created when a shell is buried in sediment and subsequently decays or dissolves, leaving an impression or cavity in the surrounding material. This mold captures the external shape and details of the shell, making it a valuable fossil for studying ancient marine life. In some cases, minerals may fill this mold over time, creating a cast that replicates the original shell's form. Such molds and casts are important in Paleontology for understanding the diversity and evolution of shell-bearing organisms.