A great note to end on.

I’m not much of a scientist, but I appreciate the amount of thought that was put into the Biomass story!

This makes me further suspect it was humans who created the Biomass, IDK though I forgot some stuff from the other book

[A planet between the two stars with have increasingly stochastic orbit until it crashes into one of the stars.]

Typo?

Worldbuilding, especially the scientific side of it, isn’t my forte, but I’m always a fan of good stories that also have a lot of thought put into the world. :)

I hadn’t thought about all life on all planets in this fictional universe being similar in contrast to some other sci-fi series, but I suppose that would only make sense if one bug could threaten all of it.

I wonder how one would define the concept of life in another universe where life appeared totally different.

I will say, Dr. Mortabio is all but breaking the fourth wall here when he acknowledges the sci-fi tropes :p but, IIRC (I have already forgotten some stuff from The Biomass), Dr. Mortabio came from a “non-sentient” planet where people weren’t aware of life on other planets so I guess he would think of things in terms of sci-fi tropes.

I would replace the need for oxygen with a need to formulate energy as the reason so few flying sentient beings exist. Making energy is a direct user of oxygen, but takes into account the need for emence amounts of energy in the form of food as well.

How big are they? Just wondering.

Interesting thought with the coat colors, though on earth camouflage comes top over heat regulation, even in predators, such as the white polar bear. Why is this not the case here? Are there no predators at all on the planet?
Is the biomass sentient? I thought is wasn't... Perhaps I have not gotten far enough into the story.

So they are basically octopuses! I love octopuses!
I am interested to know how they got off planet, surely the water resistance would be too much?

interesting, this is pretty solid, apart from the black holes... I can foresee several problems here, such as, where is the star? Is there one? How do the orbits work? Is the sun also orbiting around the black hole like a planet might? Then the planets around the sun? The huge changes in gravitational forces of black holes close enough to see seems... Averse, shall I say, to life.
Take the example in 'gravity' a scientifically , pretty sound film, and the planet orbiting a black hole. The planet had no land mass and no life because as the planet span huge waves were pulled across it's surface similar to the way the moon pull water across the earth. Just bigger. Such movement restricts the ability of life to evolve, any time molecules get close enough to interact they are shaken apart by the huge movement. There is also the matter of time distortion that occurs around black holes. Also visited is 'Gravity', objects closer to the black holes appear to move very quickly though time. They would evolve and be sentient far sooner in terms of the universe than any other species. And finally, how do they escape the lock of gravity from the black holes, and explore the universe?

What about lifeforms using CO2? All life on earth began with CO2 respiring lifeforms, then, as their numbers increased the waist product they produced began to kill them, O2. The few that could evolve to respire O2 flourished, but without the CO2 respiring micro organisms (and now plants) producing O2, we as humans would not have evolved.

I wouldn't call it 'being poisonous' to bacteria...
It is defined as a substance that is capable of causing the illness or death of a living organism when introduced or absorbed (by the living organism). It is true that we produce toxins which are harmful to bacteria and other invasive micro organisms, but we in our self's cannot be described as poisonous. In fact, our bodies are the perfect incubator and food source of a number of healthy and beneficial microbes, without which we would die. So, it is a blessing we are not in fact poisonous. The rest of your logic is mostly sound, but you will need to find another way of describing it. 'Toxic to harmful bacteria, viruses and protists' would be better.

I would have phrased it, 'all life exists in order to make more of it's self.' Rather than 'because'. It has a slightly different meaning if you use 'because'
Also, I know that you only want to talk about intelligent life, but can't be only one form of reproduction in the whole universe, purely because ours is so flawed. Before you really solidify this idea, I would look at flower reproduction, asexual reproduction, and reproduction of some marine animals that involved more than the 'conventional' two sexes. Just because the dominant species employs it, doesn't mean it is the most effective or the best way. All the other things being universal, I can kinda get behind, but here, I think more research could be done.

enjoying your writing...adding this to my favorites!

Hey! As a biochemist, I really enjoyed this - the logic behind the science of your world flows nicely and you explain things very well. You mentioned species with three sexes can be made in a lab setting, but I wonder, in your world, would there be species like clownfish, which can change sex (including reproductive functions) due to environmental selection pressure? Also, in your world, would it be possible for oxygen-independent species to arise? The first organisms on Earth were methane-dependent...would there be species like that? Perhaps species whose genetic material is perhaps sulphur-based, instead of oxygen-based like our DNA?

Overall, great read and nicely-written :)