If one were to follow any particle of the particle physics zoo, they all end up as being atoms, whether hydrogen or helium or some other atom, that is what they end-up as. An adult human being has independent existence. But the arm or finger or hand or leg or feet or toe or nose or chest or any organs are not independent existing parts. Same thing for particles of the particle physics zoo. These are pieces of atoms.
Atoms are the start of physics.
Back in December of 1998 I started to talk about the lowest things of physics, of biology, of mathematics, of sociology. This is a very important topic. And I want to add on more subjects such as the lowest thing for nuclear physics and the lowest things for astronomy and the lowest thing for engineering and the lowest thing for moving astro bodies. Lowest things are important because they give one the correct understanding and the correct theory of the subject. For example, without knowing the lowest thing in particle physics, which is the atom itself, then you mistakenly waste tremendous time on particle physics zoo, and you create fake theories such as the quark theory, the standard model theory, the superstring and string theories, the Higgs theory and many more false theories.