  The $S$-wave eigenstates of tetraquarks of type $s u \bar d \bar b$ with
J$^{P}$ = 0$^{+}$, 1$^{+}$ and 2$^{+}$ are studied within a simple quark model
with chromomagnetic interaction and effective quark masses extracted from meson
and baryon spectra. It is tempting to see if this spectrum can accommodate the
new narrow structure X(5568), observed by the D\O~~Collaboration, but not
confirmed by the LHCb Collaboration. If it exists, such a tetraquark is a
system with four different flavors and its study can improve our understanding
of multiquark systems. The presently calculated mass of X(5568) agrees quite
well with the experimental value of he D\O~~Collaboration. Predictions are made
for the spectrum of the charmed partner $s u \bar d \bar c$. However we are
aware of the difficulty of extracting effective quark masses, from mesons and
baryons, to be used in multiquark systems.
