  A circumstellar corona is proposed for a strange quark-cluster star during an
accretion phase, that could be essential to understand the observations of the
puzzling symbiotic X-ray system, 4U 1700+24. The state of cold matter at
supranuclear density is still an important matter of debate, and one of the
certain consequences of strange star as the nature of pulsars is the self-bound
on surface which makes extremely low-mass compact objects unavoidable. In
principle, both the redshifted O VIII Ly-$\alpha$ emission line and the change
of the black-body radiation area could be understood naturally if 4U 1700+24 is
a low-mass quark-cluster star in case of wind-accretion.
