How about x=life?
Miller and Urey conducted an experiment (don't fail me now, class 12 biology) wherein they simulated the primitive conditions of earth - the primordial soup of methane ammonia water and hydrogen. An environment without oxygen in the atmosphere to an extent that it exists today. You know what they found? They found that an electric spark caused the formation of molecular aggregates.
At the end of one week, Miller observed that as much as 10-15% of the carbon was now in the form of organic compounds. Two percent of the carbon had formed some of the amino acids which are used to make proteins. Perhaps most importantly, Miller's experiment showed that organic compounds such as amino acids, which are essential to cellular life, could be made easily under the conditions that scientists believed to be present on the early earth.
You may or may not want to read about abiogenesis on this page
Protobionts and coacervates are aggregates that have been synthesised. They can inaccurately replicate, but have no life in them.
So what is the step between non-living and living? What separates a living cell from it's constituents? That's a question science and logic have still not been able to answer.
What has been put into each "life-form" from borderline non-living virii to fully conscious and sentient human beings that causes them to reproduce? Do they know about death? How do they reason that at some time they should propagate themselves to generate further life?
You might have heard the statement omnis cellulae a cellulae. It means that cells arise from pre-existing cells only. That is the mystery of life. You can take all the parts of a cell separately and put them into a petridish but a new cell will not arise from the constituents as such.
Why did life decide to evolve? Why are we not single cells floating around in water? How does each cell of an organism contain the exact genetic information as all the others, yet behave differently?
The concept of logic was invented by human beings.
A kangaroo has ears, a tail, 4 limbs, a nose, a brain, 2 eyes. A rabbit has ears, a tail, 4 limbs, a nose, a brain, 2 eyes. Even at the molecular level, both are composed of molecules of C, H, O, N, S, Ca, P, K, Mg, Fe, etc. Hence a rabbit and a kangaroo are actually the same thing, right? Even you are the same as a mixture of the compounds of the aforementioned elements. Hence you are a rabbit.