  A hypothesis based on observational and theoretical results on the origin of
C-type asteroids and carbonaceous chondrites is proposed. Asteroids of C-type
and close BGF-types could form from hydrated silicate-organic matter
accumulated in the cores of water-differentiated (due to 26Al and other
short-lived isotopes decay) bodies existed in the growth zones of Jupiter.
Gravitational scattering of such bodies by Jupiter at its final stage of
formation to the main asteroid belt might have led to fragmentation and
re-accretion of their primitive materials on the surfaces of many asteroids
and/or asteroid parent bodies. The hypothesis makes clear a row of
long-standing puzzling facts, the main of which are as follows. The low-albedo
and carbonaceous-chondritic surface properties of (1) Ceres contradict to its
probable differentiated structure and icy crust (e. g., Thomas et al., 2005,
Nature 437: 224-226; Castillo-Rogez et al., 2010, Icarus 205, 443-459), but it
could be explained by the process of primitive matter fall. Atypical hydrated
silicates (probably, as a component of carbonaceous-chondritic matter) are
found on the surfaces of many asteroids of high-temperature types (Rivkin et
al., 1995, Icarus 117: 90-100; Rivkin et al., 2000, Icarus 145: 351-368;
Busarev, 1998, Icarus 131: 32-40; Busarev, 2002, Solar System Research 36:
39-47) that may be a consequence of the carbonaceous-chondritic matter
precipitation on their surfaces. Some carbonaceous chondrites are
unidirectionly magnetized (e. g., Stacey et al., 1961, J. Geophys. Res. 66:
1523-1534; Butler, 1972, Earth Planet. Sci. Lett. 17: 120-128) which may be a
result of their stay on the surface of an early differentiated asteroid parent
body having melted interiors and a strong magnetic field.
