Each cell expresses, or turns on, only a fraction of its genes. The rest of the genes are repressed, or turned off.
The turned on genes are then first transcribed into messenger RNA by the process of Transcription.
Then the mRNA is Translated into protein by the process called Translation.
This is how the specific genes are expressed.
Totipotent cells can differentiate into more types of cells
When the organism dies in a moist or wet area the organism gets covered in mud and the mud hardens like a rock.