At least they didn't call it an "angel" particle, like in the previous submissions.
So yes, if you were attracted to this article because you thought they found a new fundamental particle, then it was clickbait. But the real point is that it's a Majorana fermion (with well-defined momentum eigenstates, a scattering matrix, etc.).
It's possible in the future that we discover neutrinos are Majorana fermions
https://en.wikipedia.org/wiki/Double_beta_decay#Neutrinoless...
at which time they will be "fundamental Majorana fermions"... and then discover after that the neutrinos are just composite particles.
https://arxiv.org/abs/1510.07988
(There are some subtleties here. Some quasi-particles don't have all the properties we normally associate with fundamental particles. And there are weak theoretical arguments that some fundamental particles can't be composite unless their constituents have properties that are subjectively inelegant.)
Obviously there can be future theory were the electron has internal structure, but it will be a breakthrough, not a small fix.
The theoretical and experimental value of g for a muon almost agree, but only 10 digits. So there is a small chance of something interesting there. But IIRC most people think that it may be a new particle in the cloud of virtual particles, not an internal structure of muons.
Protons and neutrons have internal structure, a lot of internal structure, so the value of g is a difficult to calculate number that is not 2. In particular, g=+5.6 and g=-3.8.
All bosons (e.g. photons) are their own antiparticle, so this is a rare instance of science writing where the headline is LESS interesting than the actual work done.
> Physicists Just Generated a Particle That Acts as Its Own Antiparticle
[...]
> Physicists now have the next best thing – a particle-like system that behaves just like the kind of matter Majorana predicted