When this phrase excites you, go read the book now;

Their main spacecraft was a hard crystalline spherical shell about four centimeters across with a rather "large" miniature black hole at the center. At 11-billion tons mass, the black hole provided 180 thousand gees at the surface of the crystal sphere. Although far from the 67-billion gees that the cheela lived in at the surface of the neutron star, it was enough to keep their electron structure in its degenerate form.

Do it now!