[JethroHathAWay]

but every single cell of our mortal coil's source is from star dust.

I have always heard this; from Sagen probably. Is it true? How do they know this?

[inquest]

They know there's really only one way that the heavy elements (that is, pretty much anything other than hydrogen and helium) can be created, and that's through the immense pressures that exist within the interior of a sun. Many stars (what I believe they call 1st-generation stars) have only hydrogen and helium, but when they examine the remnants from, say, a supernova, they find the rest of the elements.

[RightWhale]

How do they know this?

Every element heavier than the few lightest atom types had to be formed in novas or supernovas, exploded stars. Hydrogen in our cells might not have part of a star, but iron would have been.

[longshadow]

I have always heard this; from Sagen probably. Is it true? How do they know this?

The only mechanism that science can find for production of significant quantities of matter heavier than helium is through processes associated with the nuclear reaction inside of stars.

Anything that is made out of atoms other than hydrogen or helium virtually had to come from material that was ejected from some long-since dead star. Hence almost everything you come in contact every day is made from "star-dust."