blood stone
when you experience something so horrific your poop fills your lower bowels and petrifies into a hard ball tearing your anus open and covering your turd with blood. One solid bloody mass.
We heard the screaming saw him crying and clenching ass checks in pain, he could have at least flushed the blood stone he left behind.
blood from a stone
An unlikely event requiring much effort.
Trying to get you to find a job is like trying to get blood from a stone.