A serious objection against the successful Urey-Miller experiments as a guideline to how prebiotic life emerged is that the atmosphere was not at that time reducing (reducing means that there are atoms able to donate electrons, oxygen does just the reverse).
This objection could serve as a motivation for assuming that prebiotic life evolved in mantle. For detailed vision about underground prebiology see the article More Precise TGD Based View about Quantum Biology and Prebiotic Evolution. This model predicts that Cambrian Explosion lasting for 20-25 million years was associated with a sudden expansion of Earth radius by a factor 2 about 542 million years ago.
Expanding Earth hypothesis would be reduced in TGD framework to the replacement of continuous cosmic expansion for astrophysical objects with a sequence of short expanding periods followed by long non-expanding periods in accordance with the finding that astrophysical objects do not participate in cosmic expansion (see this). This sudden expansion would have led to a burst of underground oceans to the surface of Earth and generated the oceans as we know them now. This prediction is consistent with the assumption that the hydrothermal water explaining the above described finding originated from seawater.
A killer prediction is that underground life would have developed photosynthesis, and the lifeforms would have been rather highly evolved as they burst on the surface of Earth. How this was possible is one of the questions for which answer is proposed in the article More Precise TGD Based View about Quantum Biology and Prebiotic Evolution. The new physics predicted by TGD - in particular hierarchy of Planck constants identified in terms of dark matter - is an essential element of the model.
For a summary of earlier postings see Links to the latest progress in TGD.