  The almost 7 decades lasting futile attempts to understand the possible
physical content of the third Wigner representation class (the infinite spin
class) came to a partial solution with the 2006 discovery of existence of
string-localized spacetime covariantizations . This has led to a still ongoing
vast generalization of renormalizability to fields with arbitrary high spin and
a better understanding of the origin of partial invisibility as observed in the
confinement of gluons and quarks. The present note explains the total
(non-gravitational) invisibility of fields associated to the third Wigner
representation class. The last section presents a critical look at the
possibility that third class Wigner matter may play a role in dark matter
formation.
