In 1997, a year after the rediscovery of banana liquid crystals^1,2, the Boulder group showed that achiral, bent-core liquid crystal molecules form polar, chiral smectic phases when the molecules are tilted in the layers, the first example of spontaneous chiral resolution in a fluid³. The B4 phase was also observed around this time, and the dark conglomerate a few years later, but their underlying structures, though the subject of much speculation, were not understood. Ten years later, optical microscopy, x-ray scattering, AFM and freeze-fracture transmission electron microscopy have resulted in the first complete picture of these mysterious phases. In both phases, the layers have significant saddle splay curvature.The B4 phase is a unique variant of the twist grain boundary phase, being made of bundles of twisted, rope-like smectic ribbons (helical nanofilaments) of finite lateral extent, which pack together to produce macroscopic left- and right-handed domains that rotate plane-polarized light and can typically be resolved in the microscope.⁴ The dark conglomerate (DC) phase is an optically isotropic, three-dimensional assembly of curved smectic layers that form a sponge-like structure filled with smectic layers that minimizes the global free energy. The dark conglomerate phase exhibits little birefringence but is optically active and exhibits large homochiral domains in cells.⁵