Carbon
Coal and diamonds are both forms of carbon.
carbon
Neon is chemically inert. It doesnt react with any other element and (to the best of my knowledge) has no role in living things. So I would comment that the element neon is not found inside living things.
The most common element found in all living things is not, as you would think, oxygen. It is carbon an can be found in every living organism. That is why organic material gives of Carbon and Oxygen as it rots or burns.
Carbon is the element found in diamonds, pencils (graphite), and is abundantly present in various forms on Earth.
Carbon.
hydrogen
The element that is most abundant in living things is carbon. The other five elements that are most abundant in living things are hydrogen, nitrogen, oxygen, phosphorus and sulfur.
diamonds found inside the volcano
Iron compounds exist in all living organisms.
Uonic bonds
Carbon in a tight crystal lattice form can be found in all diamonds.