Lavoisier once said: nothing is lost, nothing is created, everything is transformed.

It is possible matter in our universe came to ours from another one, transforming itself....but it reminds me a bit about explaining how life started on Earth by arguing it came from Mars (panspermia), but then how did it start on Mars?

We don't know much about the universe! But the infinite-finite issue is not just a matter of knowledge but also of reasoning.

It should be pointed out that this practice of refusing infinite values for measurable quantities does not come from a priori or ideological motivations, but rather from more methodological and pragmatic motivations. One of the needs of any physical and scientific theory is to give usable formulas that correspond to or at least approximate reality. As an example if any object of infinite gravitational mass were to exist, any usage of the formula to calculate the gravitational force would lead to an infinite result, which would be of no benefit since the result would be always the same regardless of the position and the mass of the other object. The formula would be useful neither to compute the force between two objects of finite mass nor to compute their motions. If an infinite mass object were to exist, any object of finite mass would be attracted with infinite force (and hence acceleration) by the infinite mass object, which is not what we can observe in reality.