For example, the earth is more than 6000 kilometers in diameter. If pressed into black hole density, the diameter of the earth will not exceed 20 cm, which is about the size of a football.
Except for black holes, all substances in the universe are made up of atomic basic units. Black holes probably have no atoms, because the density is too high and they collapse. The atoms have been crushed, and even the protons and neutrons that make up the atoms have been crushed.