  We analyse the decay $\Theta_s(1/2^+)\to NK$ in a non-relativistic Fock space
description using three and five constituent quarks for the nucleon and the
pentaquark, respectively. Following Jaffe and Wilczek \cite{jw}, we assume that
quark-quark correlations in spin-zero state play an important role for the
pentaquark internal structure. Within this scenario, a strong dynamical
suppression of the decay width is shown to be possible only if the pentaquark
has an asymmetric "peanut" structure with the strange antiquark in the center
and the two extended composite diquarks rotating around. In this case a decay
width of $\simeq$ 1 MeV may be a natural possibility.
