Since several decades, a particular attention has been devoted to hadrons with anomalous properties [1-5].On the experimental side, the search has been very difficult and disappointing.For instance, in the early 60's, there has been some claims for baryon resonances with strangeness S =+1, the so-called Z baryons, while the established baryons have either S =0 or S ＜ 0.But the Z spectrum was based on somewhat hazardous analyses of K+-nucleon scattering data without spin observables, and it faded away.It reappeared under the name of θ pentaquark, but it was never firmly established.