What is "pre-cell"

A pre-cell is a hypothetical lipid-based structure that, under the RNA world hypothesis, could have confined RNA in ancient times. A pre-cell allowed the RNA to remain in close proximity with other RNA molecules, keeping them concentrated and allowing for an increased reaction rate of enzymes. Pre-cells would have had semi-permeable membranes, allowing only certain molecules to pass through. These enclosed structures may have facilitated natural selection in RNA molecules.