  Evidence for excitation of exotic S=+1 pentaquark degrees of freedom is
presented by studying optical-potential fits to K^+ - nucleus total, reaction
and elastic-differential cross section data at p(lab) = 500 - 700 MeV/c.
Estimates of the underlying two-nucleon absorption K^+ n N --> Theta^+ N
reaction cross section are made and are used for discussing the anticipated
cross section of the strangeness exchange reaction K^+ N --> pi Theta^+.
