The next doll down emanated from particle accelerators and their detectors which were first built in the 1950s. This led to further splitting the protons and neutrons in atomic nuclei into smaller, more “elemental” particles: hadrons.
Particle accelerators proliferated hadrons into such a prodigious variety that it prompted Wolfgang Pauli to remark: Had I foreseen this I would have gone into botany.
By the late 1960s, a “depressingly large number” of hadrons had been found. Hadrons were but a nested doll, not the smallest doll in Matryoshka reality. Hadrons are comprised of quarks.
For decades, hadrons were known to be of only 2 families: baryons, composed of 3 quarks, and mesons, comprising 1 quark and 1 antiquark. In 2014, a new meson family was discovered: a tetraquark, with 2 quarks and 2 antiquarks.
Like hadrons, quarks have their own varieties, called flavors, which are determined by their spin and symmetry.
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Going bottoms-up: quarks combine to form families of hadrons, which join in threesomes to form protons and neutrons (2 types of baryons), which are enslaved by the strong nuclear force to create atomic nuclei, which combine with electrons, bound together by the electromagnetic force, to create atoms. By ionic attraction, atoms congregate into molecules, which make up everyday matter. Bear in mind that all these particles are nothing more than intense interactions of localized coherent energy fields, posing as something solid.