If stars can’t fuse iron, where do it and all other heavier elements come from?
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You can fuse atoms (technically, atomic nuclei) and get a product that is heavier than iron. People do this in labs, which is how we create new elements. What you can’t do is fuse two atoms together to make an atom heavier than iron *and get fusion energy out of it*.
Fusion that gives off energy can be a self sustaining process. You fuse hydrogen into helium, which gives off energy, and you can use some of that energy to fuse more hydrogen into helium. This is what happens in the center of the Sun. Fusing heavier elements doesn’t give off energy, so it can’t be a self sustaining process. That doesn’t mean it can’t happen, but it’s hard to make it happen. You can’t have a star fusing iron into tellurium, because fusing iron doesn’t give off energy. The reaction would stop pretty quickly if you didn’t keep putting energy in to make it go.
If you’re willing to put a lot of energy into it and not get energy out, you can fuse pretty much whatever you want. People can do this with particle accelerators. When a star explodes and becomes a supernova, there’s a lot of energy in that explosion, some of which can go into fusing elements heavier than iron.
The fact that it’s really hard to create elements heavier than iron is why there’s so much more silicon and iron around than, say, gold or uranium.
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