Answer
No, it was literally a churning.
However, what we ordinarily understand as churning is only the gross, physical aspect. Along with the physical process, many mantras and subtle spiritual energies were also employed by the rishis. They applied their mastery over subtle material energy.
So it was not merely a mechanical process as we might imagine. Everywhere in creation there are subtle energies in addition to gross matter.
We have already discussed that every cell in the human body contains the information of the entire body. Modern science has demonstrated this through DNA. Each cell carries the complete genetic information of the body—information about your physical characteristics, tendencies, and many aspects of your individuality.
From that perspective, it becomes reasonable to understand that such extraordinary processes were possible.
The sages did not possess mechanical devices as we do today, but they possessed knowledge and technologies that worked through subtle energies.
Even today, cloning technology demonstrates that living organisms can be replicated. We have examples of cloning animals, which shows that material science itself has begun to approach concepts that once seemed impossible.
We really have no idea how advanced material science was in ancient times.
The limitation of modern science is that it studies only gross matter.
The Vedic sages, however, understood an entire range of subtle material energies in addition to gross matter. Modern science knows very little about these subtle dimensions.
Who were the scientists of the subtle body?
The rishis.
By combining knowledge of both gross and subtle matter, they were capable of engineering achievements that appear miraculous from today's perspective.
