Hence why the guess is that it was clays not crystals. Clays are more complex mechanically, somewhat porous, kind of work as a prototype cell wall. Consensus is more on the side of biofilms than crystals at that point. There are relatively simple multiphase processes that can create such lipid and biological bubbles. Just check how micelles form from random hydrocarbons in water with additives. The more stable micelles would allow biofilms to form inside, and so it goes.

Generally cell wall first hypothesis over RNA/peptides first.

Through such a biofilm micelle only certain chemicals can get in or out. This favors particular molecules "crystallizing" (or rather polymerizing) inside such micelles.