Figure 5-5 Sidney Fox’s proteinoid microspheres can absorb materials from the environment, grow and divide in two by fission.

It is a thermodynamic principle, in conclusion, that spontaneous reactions are more likely to occur on surfaces than in space, and it is reasonable therefore to conclude that the first metabolic structures were two-dimensional systems and not three-dimensional ones. Rather that in a primitive broth, in other words, chemical evolution could well have started on primitive pizzas.
Bernal and Cairns-Smith proposed that the first metabolic surfaces were provided by crystals of clay, and therefore that life did literally originate in mud, because clays can adsorb a vast range of organic molecules.