  Models in which the "dark" halo particles have mutual and potentially also
appreciable nuclear interactions have been considered by various authors. In
this note we briefly point out strategies for a most sensitive search for these
particles. We show that a particular matter/anti-matter symmetric variant due
to Farrar et al. is excluded by combining bounds on proton decay from various
experiments and from super-Kamiokande and atmospheric neutrino measurements at
super-Kamiokande.
