Survival cell
The survival cell is the carbon-fibre structure the driver sits in, built to stay intact when everything attached to it does not.
Also called monocoque, tub
Wings, suspension and bodywork are designed to break away and absorb energy. The cell is designed to do the opposite: it must pass a set of static and impact tests before a car is allowed to race.
Almost every accident that looks unsurvivable and is not comes down to this, plus the halo above it and the energy taken out by everything that detached on the way.