Tubeworms live around deep-sea vents

Actually this is not a theory. Photosynthesis came millions of years later than life. Plants are evolved from animals, not the other way around. Basic animals are less evolved than basic plants.

Plants and animals evolved from different lineages of eukaryotic organisms. They share a common ancestor, but plants did not evolve from animals. Plants evolved from green algae, while animals evolved from colonial protists.

I also take exception with the concept of "more" or "less" evolved. Do you mean "complexity"?

He is right though that, "Photosynthesis came millions of years later than life." And the parent post's claim, "There's a theory that life actually originated not directly through photosynthesis based life," misrepresents that it is a commonly held view that life originated not directly through photosynthesis based life. It is generally understood that life predates photosynthesis.

Yes, they are right that photosynthesis came later, but then veered way off track saying that plant evolved from animals.

I probably should have acknowledged they were right about that, but I was so jarred by what they were wrong about it's the only thing that had my focus.

Ah I am sorry, I was not precise in my wording and thus wrong. I meant animals as in cellular organisms that are mobile and eat matter. A lot of people think plants are a prerequisite for animals which is wrong in at least one way. I studied biology so I should have worded it correctly. I should have said that heterotrophs and autotrophs with a basic form of photosynthesis -that looks nothing like the form it has nowadays- first colonized the world. Then multicellular animals without hard bits and less defined organs came into existence and shortly followed by "plants" like kelp and other loosely structured colonies of algae. Then a long time after that real plants and land plants and then animals with hard bits. I am telling this from memory and should probably check it. I was reacting in a way I usually react when someone says something stupid in a pub. But this is of course a more learned platform and I should have reacted accordingly. With more evolved we mean: more steps between the common ancestor than the compared one, when defined. I must admit, it is not based in facts, to make an extreme point: we have a common ancestor with sponges. But sponges have not evolved a lot since they first came on the scene. We are more evolved that sponges. Similarly, early plants and sponges had a common ancestor. Early plants are probably more evolved than sponges.