  The newly observed $\Theta^+$ resonance is believed to be a pentaquark with
the constituent quarks $uudd\bar s$. There are a few options for the
constituent quark structure. Some advocate diquark-diquark-antiquark
$(ud)$-$(ud)$-$\bar s$ while others favor diquark-triquark $(ud)$-$(ud\bar s)$.
We use the color-spin hyperfine interaction to examine the energy levels of
these structures, and we find that the diquark-diquark-antiquark structure is
slight favored. We proceed to write down the flavor triplet and antisextet of
the charmed or bottomed exotic baryons with internal $qqqq\bar Q$ quarks. We
also estimate the mass of $\Theta_c^0$ and $\Theta_b^+$.
