Before winging into strings, a brief digression on quanta that aren’t, but act as if they are.
“These particles are just smoke and mirrors, handy mathematical tricks and nothing more. Or are they?” ~ English physicist Andrea Taroni
Quasiparticles are emergent phenomena that behave as quanta but are illegitimate in the sense of being a fermion or boson per se. Quasiparticles are to quantum mechanics what epigenetics is to genetics: potent, but not quite kosher. Both illustrate the deep, entangled intricacy that characterizes Nature.
Quasiparticles are employed to explain oscillations, which are the fluctuations in fields. Phonons explain mechanical vibrations. Plasmons are quantized plasma oscillations. Magnons quantize the waveform which personifies the spin property of all quanta. Excitons are the quantized excitement of nothingness (holes) that exist after electrons have departed.