Answer;
Mold
A mold is the cavity left behind in the rock after an organism's hard part has dissolved.
Step-by-step explanation;
- When plants and animals die they undergo decay. when the soft tissues of an organisms decay in sediment, the hard parts such as bones may be left behind.
- Carbonization or distillation is the process that yields detailed carbon impression of dead organisms on a sedimentary rock.
- When an organisms completely dissolves in a sedimentary rock, an impression of its exterior may be left in the rock. This impression is called an external mold.
- When the mold gets filled with minerals, it becomes a cast. when sediments or minerals fills the internal cavity of an organism such as skull, an internal mold forms.