That is according to the wikipedia article - and how amazing it is that such an article should even exit, every time I look up something so arcane in wikipedia and it is actually there I'm still surprised, it is one of the very best things to come out of the web revolution - essentially the same thing.

The 'somewhat' I guess refers to the word 'particles' used in the title, that should have been 'quasiparticles' in stead (in other words, particles that can not be observed directly) ?