Ashes of dying stars? Every naturally-occurring element heavier than lithium (if you've taken yours today) was once at the core of a star. All your carbon, nitrogen, oxygen, sodium, magnesium, aluminium, silicon, phosphorus, sulphur, chlorine and the rest (and some of the hydrogen too). That makes me feel good, how about you?

As for your cells (I'm not a cellist McG, though I play the fiddle a bit), you're not so much a unity as a coalition, or better still an ecosystem. Even the cells themselves are symbiotic systems, it's believed that the mitochondria are ancient bacteria that came to live with the nucleic DNA and they have their own pedigree separate from the nucleic line.