  In this talk we report on the use of a chiral unitary approach for the
interaction of the octets of meson and baryon and the octet of mesons with the
decuplet of baryons. Two octets of $J^{\pi}=1/2^-$ baryon states and a singlet
are generated dynamically in the first case, resulting in the case of
strangeness $S=-1$ in two poles of the scattering matrix close to the nominal
$\Lambda(1405)$ resonance. In the second case many resonances are also
generated, among them an exotic baryon with S=1 corresponding to a $\Delta K$
resonance. We make suggestions of experiments which could show evidence for the
existence of these states.
