This phase is favored in detergent-in-water solutions and has a packing ratio of less than one. The micellar population in a detergent/water mixture cannot increase without limit as the detergent to water ratio increases. In the presence of low amounts of water, lipids that would normally form micelles will form larger aggregates in the form of micellar tubules in order to satisfy the requirements of the hydrophobic effect.  These aggregates can be thought of as micelles that are fused together. These tubes have the polar head groups facing out, and the hydrophobic hydrocarbon chains facing the interior. This phase is only seen under unique, specialized conditions, and most likely is not relevant for biological membranes.