[AnimalMuppet]

How common? I don't know. But it could work something like this:

All standard particles are composed of AnimAlMuppet's Magic Particles (AMMPs). AMMPs each have 1 eV of mass. An electron, for example, is made up of 511,000 AMMPs. We calculate a mass of 511 keV, in good agreement with experiment.

Note well: I have no idea if these people are doing something like that. All I've seen is the abstract.